diff --git a/doc/old/cross.txt b/doc/old/cross.txt
index c0885c08176e..ff9fefb04a86 100644
--- a/doc/old/cross.txt
+++ b/doc/old/cross.txt
@@ -78,7 +78,7 @@ Step 2: build kernel headers for the target architecture
 ---
 {stdenv, fetchurl}:
 
-assert stdenv.system == "i686-linux";
+assert stdenv.buildPlatform.system == "i686-linux";
 
 stdenv.mkDerivation {
   name = "linux-headers-2.6.13.1-arm";
diff --git a/nixos/lib/make-system-tarball.nix b/nixos/lib/make-system-tarball.nix
index 92539235be75..846013b02d14 100644
--- a/nixos/lib/make-system-tarball.nix
+++ b/nixos/lib/make-system-tarball.nix
@@ -1,7 +1,7 @@
 { stdenv, perl, pixz, pathsFromGraph
 
 , # The file name of the resulting tarball
-  fileName ? "nixos-system-${stdenv.system}"
+  fileName ? "nixos-system-${stdenv.hostPlatform.system}"
 
 , # The files and directories to be placed in the tarball.
   # This is a list of attribute sets {source, target} where `source'
diff --git a/nixos/lib/qemu-flags.nix b/nixos/lib/qemu-flags.nix
index f115ca5ac000..779f0377a512 100644
--- a/nixos/lib/qemu-flags.nix
+++ b/nixos/lib/qemu-flags.nix
@@ -14,12 +14,12 @@ in
 
   qemuSerialDevice = if pkgs.stdenv.isi686 || pkgs.stdenv.isx86_64 then "ttyS0"
         else if pkgs.stdenv.isAarch32 || pkgs.stdenv.isAarch64 then "ttyAMA0"
-        else throw "Unknown QEMU serial device for system '${pkgs.stdenv.system}'";
+        else throw "Unknown QEMU serial device for system '${pkgs.stdenv.hostPlatform.system}'";
 
   qemuBinary = qemuPkg: {
     "x86_64-linux" = "${qemuPkg}/bin/qemu-kvm -cpu kvm64";
     "armv7l-linux" = "${qemuPkg}/bin/qemu-system-arm -enable-kvm -machine virt -cpu host";
     "aarch64-linux" = "${qemuPkg}/bin/qemu-system-aarch64 -enable-kvm -machine virt,gic-version=host -cpu host";
     "x86_64-darwin" = "${qemuPkg}/bin/qemu-kvm -cpu kvm64";
-  }.${pkgs.stdenv.system} or "${qemuPkg}/bin/qemu-kvm";
+  }.${pkgs.stdenv.hostPlatform.system} or "${qemuPkg}/bin/qemu-kvm";
 }
diff --git a/nixos/modules/installer/cd-dvd/installation-cd-base.nix b/nixos/modules/installer/cd-dvd/installation-cd-base.nix
index 1453e8082b0d..24070a786945 100644
--- a/nixos/modules/installer/cd-dvd/installation-cd-base.nix
+++ b/nixos/modules/installer/cd-dvd/installation-cd-base.nix
@@ -16,7 +16,7 @@ with lib;
     ];
 
   # ISO naming.
-  isoImage.isoName = "${config.isoImage.isoBaseName}-${config.system.nixos.label}-${pkgs.stdenv.system}.iso";
+  isoImage.isoName = "${config.isoImage.isoBaseName}-${config.system.nixos.label}-${pkgs.stdenv.hostPlatform.system}.iso";
 
   isoImage.volumeID = substring 0 11 "NIXOS_ISO";
 
diff --git a/nixos/modules/installer/cd-dvd/sd-image-aarch64.nix b/nixos/modules/installer/cd-dvd/sd-image-aarch64.nix
index bd6cf029967c..86e19f3da562 100644
--- a/nixos/modules/installer/cd-dvd/sd-image-aarch64.nix
+++ b/nixos/modules/installer/cd-dvd/sd-image-aarch64.nix
@@ -16,7 +16,8 @@ in
   ];
 
   assertions = lib.singleton {
-    assertion = pkgs.stdenv.system == "aarch64-linux";
+    assertion = pkgs.stdenv.hostPlatform.system == "aarch64-linux"
+      && pkgs.stdenv.hostPlatform.system == pkgs.stdenv.buildPlatform.system;
     message = "sd-image-aarch64.nix can be only built natively on Aarch64 / ARM64; " +
       "it cannot be cross compiled";
   };
diff --git a/nixos/modules/installer/cd-dvd/sd-image-armv7l-multiplatform.nix b/nixos/modules/installer/cd-dvd/sd-image-armv7l-multiplatform.nix
index 0c89eb533359..695c79ca1707 100644
--- a/nixos/modules/installer/cd-dvd/sd-image-armv7l-multiplatform.nix
+++ b/nixos/modules/installer/cd-dvd/sd-image-armv7l-multiplatform.nix
@@ -16,7 +16,8 @@ in
   ];
 
   assertions = lib.singleton {
-    assertion = pkgs.stdenv.system == "armv7l-linux";
+    assertion = pkgs.stdenv.hostPlatform.system == "armv7l-linux"
+      && pkgs.stdenv.hostPlatform.system == pkgs.stdenv.buildPlatform.system;
     message = "sd-image-armv7l-multiplatform.nix can be only built natively on ARMv7; " +
       "it cannot be cross compiled";
   };
diff --git a/nixos/modules/installer/cd-dvd/sd-image-raspberrypi.nix b/nixos/modules/installer/cd-dvd/sd-image-raspberrypi.nix
index 78ea3f1a205c..e395b265d15e 100644
--- a/nixos/modules/installer/cd-dvd/sd-image-raspberrypi.nix
+++ b/nixos/modules/installer/cd-dvd/sd-image-raspberrypi.nix
@@ -16,7 +16,8 @@ in
   ];
 
   assertions = lib.singleton {
-    assertion = pkgs.stdenv.system == "armv6l-linux";
+    assertion = pkgs.stdenv.hostPlatform.system == "armv6l-linux"
+      && pkgs.stdenv.hostPlatform.system == pkgs.stdenv.buildPlatform.system;
     message = "sd-image-raspberrypi.nix can be only built natively on ARMv6; " +
       "it cannot be cross compiled";
   };
diff --git a/nixos/modules/installer/cd-dvd/sd-image.nix b/nixos/modules/installer/cd-dvd/sd-image.nix
index 2371be9d89a1..b6e1d11c2b54 100644
--- a/nixos/modules/installer/cd-dvd/sd-image.nix
+++ b/nixos/modules/installer/cd-dvd/sd-image.nix
@@ -22,7 +22,7 @@ in
 {
   options.sdImage = {
     imageName = mkOption {
-      default = "${config.sdImage.imageBaseName}-${config.system.nixos.label}-${pkgs.stdenv.system}.img";
+      default = "${config.sdImage.imageBaseName}-${config.system.nixos.label}-${pkgs.stdenv.hostPlatform.system}.img";
       description = ''
         Name of the generated image file.
       '';
@@ -102,7 +102,7 @@ in
         mkdir -p $out/nix-support $out/sd-image
         export img=$out/sd-image/${config.sdImage.imageName}
 
-        echo "${pkgs.stdenv.system}" > $out/nix-support/system
+        echo "${pkgs.stdenv.buildPlatform.system}" > $out/nix-support/system
         echo "file sd-image $img" >> $out/nix-support/hydra-build-products
 
         # Create the image file sized to fit /boot and /, plus 20M of slack
diff --git a/nixos/modules/installer/netboot/netboot.nix b/nixos/modules/installer/netboot/netboot.nix
index ea640173c6dd..303d9fce3f9a 100644
--- a/nixos/modules/installer/netboot/netboot.nix
+++ b/nixos/modules/installer/netboot/netboot.nix
@@ -25,7 +25,7 @@ with lib;
 
     # !!! Hack - attributes expected by other modules.
     environment.systemPackages = [ pkgs.grub2_efi ]
-      ++ (if pkgs.stdenv.system == "aarch64-linux"
+      ++ (if pkgs.stdenv.hostPlatform.system == "aarch64-linux"
           then []
           else [ pkgs.grub2 pkgs.syslinux ]);
 
diff --git a/nixos/modules/services/misc/gitit.nix b/nixos/modules/services/misc/gitit.nix
index 0025d96bd37b..1ec030549f98 100644
--- a/nixos/modules/services/misc/gitit.nix
+++ b/nixos/modules/services/misc/gitit.nix
@@ -10,7 +10,7 @@ let
 
   toYesNo = b: if b then "yes" else "no";
 
-  gititShared = with cfg.haskellPackages; gitit + "/share/" + pkgs.stdenv.system + "-" + ghc.name + "/" + gitit.pname + "-" + gitit.version;
+  gititShared = with cfg.haskellPackages; gitit + "/share/" + pkgs.stdenv.hostPlatform.system + "-" + ghc.name + "/" + gitit.pname + "-" + gitit.version;
 
   gititWithPkgs = hsPkgs: extras: hsPkgs.ghcWithPackages (self: with self; [ gitit ] ++ (extras self));
 
diff --git a/nixos/modules/services/networking/vsftpd.nix b/nixos/modules/services/networking/vsftpd.nix
index 1f9107c3ce9c..31e1e65fa9ca 100644
--- a/nixos/modules/services/networking/vsftpd.nix
+++ b/nixos/modules/services/networking/vsftpd.nix
@@ -99,7 +99,7 @@ let
       nopriv_user=vsftpd
       secure_chroot_dir=/var/empty
       syslog_enable=YES
-      ${optionalString (pkgs.stdenv.system == "x86_64-linux") ''
+      ${optionalString (pkgs.stdenv.hostPlatform.system == "x86_64-linux") ''
         seccomp_sandbox=NO
       ''}
       anon_umask=${cfg.anonymousUmask}
diff --git a/nixos/modules/system/boot/luksroot.nix b/nixos/modules/system/boot/luksroot.nix
index 27c1f891f485..ed8b9f01e275 100644
--- a/nixos/modules/system/boot/luksroot.nix
+++ b/nixos/modules/system/boot/luksroot.nix
@@ -324,7 +324,7 @@ in
         [ "aes" "aes_generic" "blowfish" "twofish"
           "serpent" "cbc" "xts" "lrw" "sha1" "sha256" "sha512"
 
-          (if pkgs.stdenv.system == "x86_64-linux" then "aes_x86_64" else "aes_i586")
+          (if pkgs.stdenv.hostPlatform.system == "x86_64-linux" then "aes_x86_64" else "aes_i586")
         ];
       description = ''
         A list of cryptographic kernel modules needed to decrypt the root device(s).
diff --git a/nixos/modules/virtualisation/azure-agent.nix b/nixos/modules/virtualisation/azure-agent.nix
index b7ab54aab7ec..770cefbcd511 100644
--- a/nixos/modules/virtualisation/azure-agent.nix
+++ b/nixos/modules/virtualisation/azure-agent.nix
@@ -77,7 +77,7 @@ in
   config = mkIf cfg.enable {
     assertions = [ {
       assertion = pkgs.stdenv.isi686 || pkgs.stdenv.isx86_64;
-      message = "Azure not currently supported on ${pkgs.stdenv.system}";
+      message = "Azure not currently supported on ${pkgs.stdenv.hostPlatform.system}";
     } {
       assertion = config.networking.networkmanager.enable == false;
       message = "Windows Azure Linux Agent is not compatible with NetworkManager";
diff --git a/nixos/modules/virtualisation/brightbox-image.nix b/nixos/modules/virtualisation/brightbox-image.nix
index 39a655b4c104..e716982c510a 100644
--- a/nixos/modules/virtualisation/brightbox-image.nix
+++ b/nixos/modules/virtualisation/brightbox-image.nix
@@ -26,7 +26,7 @@ in
               rm $diskImageBase
               popd
             '';
-          diskImageBase = "nixos-image-${config.system.nixos.label}-${pkgs.stdenv.system}.raw";
+          diskImageBase = "nixos-image-${config.system.nixos.label}-${pkgs.stdenv.hostPlatform.system}.raw";
           buildInputs = [ pkgs.utillinux pkgs.perl ];
           exportReferencesGraph =
             [ "closure" config.system.build.toplevel ];
diff --git a/nixos/modules/virtualisation/google-compute-image.nix b/nixos/modules/virtualisation/google-compute-image.nix
index de2c43b8a40a..4c7cffcf4557 100644
--- a/nixos/modules/virtualisation/google-compute-image.nix
+++ b/nixos/modules/virtualisation/google-compute-image.nix
@@ -14,7 +14,7 @@ in
       PATH=$PATH:${pkgs.stdenv.lib.makeBinPath [ pkgs.gnutar pkgs.gzip ]}
       pushd $out
       mv $diskImage disk.raw
-      tar -Szcf nixos-image-${config.system.nixos.label}-${pkgs.stdenv.system}.raw.tar.gz disk.raw
+      tar -Szcf nixos-image-${config.system.nixos.label}-${pkgs.stdenv.hostPlatform.system}.raw.tar.gz disk.raw
       rm $out/disk.raw
       popd
     '';
diff --git a/nixos/modules/virtualisation/virtualbox-guest.nix b/nixos/modules/virtualisation/virtualbox-guest.nix
index 78c6f740788e..834b994e92d2 100644
--- a/nixos/modules/virtualisation/virtualbox-guest.nix
+++ b/nixos/modules/virtualisation/virtualbox-guest.nix
@@ -34,7 +34,7 @@ in
   config = mkIf cfg.enable (mkMerge [{
     assertions = [{
       assertion = pkgs.stdenv.isi686 || pkgs.stdenv.isx86_64;
-      message = "Virtualbox not currently supported on ${pkgs.stdenv.system}";
+      message = "Virtualbox not currently supported on ${pkgs.stdenv.hostPlatform.system}";
     }];
 
     environment.systemPackages = [ kernel.virtualboxGuestAdditions ];
diff --git a/nixos/modules/virtualisation/virtualbox-image.nix b/nixos/modules/virtualisation/virtualbox-image.nix
index 475852d1546c..60048911658c 100644
--- a/nixos/modules/virtualisation/virtualbox-image.nix
+++ b/nixos/modules/virtualisation/virtualbox-image.nix
@@ -26,21 +26,21 @@ in {
       };
       vmDerivationName = mkOption {
         type = types.str;
-        default = "nixos-ova-${config.system.nixos.label}-${pkgs.stdenv.system}";
+        default = "nixos-ova-${config.system.nixos.label}-${pkgs.stdenv.hostPlatform.system}";
         description = ''
           The name of the derivation for the VirtualBox appliance.
         '';
       };
       vmName = mkOption {
         type = types.str;
-        default = "NixOS ${config.system.nixos.label} (${pkgs.stdenv.system})";
+        default = "NixOS ${config.system.nixos.label} (${pkgs.stdenv.hostPlatform.system})";
         description = ''
           The name of the VirtualBox appliance.
         '';
       };
       vmFileName = mkOption {
         type = types.str;
-        default = "nixos-${config.system.nixos.label}-${pkgs.stdenv.system}.ova";
+        default = "nixos-${config.system.nixos.label}-${pkgs.stdenv.hostPlatform.system}.ova";
         description = ''
           The file name of the VirtualBox appliance.
         '';
@@ -67,10 +67,10 @@ in {
           echo "creating VirtualBox VM..."
           vmName="${cfg.vmName}";
           VBoxManage createvm --name "$vmName" --register \
-            --ostype ${if pkgs.stdenv.system == "x86_64-linux" then "Linux26_64" else "Linux26"}
+            --ostype ${if pkgs.stdenv.hostPlatform.system == "x86_64-linux" then "Linux26_64" else "Linux26"}
           VBoxManage modifyvm "$vmName" \
             --memory ${toString cfg.memorySize} --acpi on --vram 32 \
-            ${optionalString (pkgs.stdenv.system == "i686-linux") "--pae on"} \
+            ${optionalString (pkgs.stdenv.hostPlatform.system == "i686-linux") "--pae on"} \
             --nictype1 virtio --nic1 nat \
             --audiocontroller ac97 --audio alsa \
             --rtcuseutc on \
diff --git a/nixos/modules/virtualisation/vmware-guest.nix b/nixos/modules/virtualisation/vmware-guest.nix
index 68930a0e3254..15c78f14c524 100644
--- a/nixos/modules/virtualisation/vmware-guest.nix
+++ b/nixos/modules/virtualisation/vmware-guest.nix
@@ -22,7 +22,7 @@ in
   config = mkIf cfg.enable {
     assertions = [ {
       assertion = pkgs.stdenv.isi686 || pkgs.stdenv.isx86_64;
-      message = "VMWare guest is not currently supported on ${pkgs.stdenv.system}";
+      message = "VMWare guest is not currently supported on ${pkgs.stdenv.hostPlatform.system}";
     } ];
 
     environment.systemPackages = [ open-vm-tools ];
diff --git a/nixos/modules/virtualisation/xen-dom0.nix b/nixos/modules/virtualisation/xen-dom0.nix
index cf57868acef9..70e575b6c0d2 100644
--- a/nixos/modules/virtualisation/xen-dom0.nix
+++ b/nixos/modules/virtualisation/xen-dom0.nix
@@ -146,7 +146,7 @@ in
   config = mkIf cfg.enable {
     assertions = [ {
       assertion = pkgs.stdenv.isx86_64;
-      message = "Xen currently not supported on ${pkgs.stdenv.system}";
+      message = "Xen currently not supported on ${pkgs.stdenv.hostPlatform.system}";
     } {
       assertion = config.boot.loader.grub.enable && (config.boot.loader.grub.efiSupport == false);
       message = "Xen currently does not support EFI boot";
diff --git a/pkgs/applications/altcoins/mist.nix b/pkgs/applications/altcoins/mist.nix
index 5f89b0a0c173..194c004f9c7f 100644
--- a/pkgs/applications/altcoins/mist.nix
+++ b/pkgs/applications/altcoins/mist.nix
@@ -4,7 +4,7 @@ let
   version = "0.11.1";
   name = "mist";
 
-  throwSystem = throw "Unsupported system: ${stdenv.system}";
+  throwSystem = throw "Unsupported system: ${stdenv.hostPlatform.system}";
 
   meta = with stdenv.lib; {
     description = "Browse and use Ðapps on the Ethereum network";
@@ -37,7 +37,7 @@ let
         url = "https://github.com/ethereum/mist/releases/download/v${version}/Mist-linux64-${urlVersion}.zip";
         sha256 = "0yx4x72l8gk68yh9saki48zgqx8k92xnkm79dc651wdpd5c25cz3";
       };
-    }.${stdenv.system} or throwSystem;
+    }.${stdenv.hostPlatform.system} or throwSystem;
 
     buildInputs = [ unzip makeWrapper ];
 
diff --git a/pkgs/applications/audio/baudline/default.nix b/pkgs/applications/audio/baudline/default.nix
index deaa3f98e52e..6827d12b3217 100644
--- a/pkgs/applications/audio/baudline/default.nix
+++ b/pkgs/applications/audio/baudline/default.nix
@@ -11,18 +11,18 @@ stdenv.mkDerivation rec {
   version = "1.08";
 
   src =
-    if stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchurl {
         url = "http://www.baudline.com/baudline_${version}_linux_x86_64.tar.gz";
         sha256 = "09fn0046i69in1jpizkzbaq5ggij0mpflcsparyskm3wh71mbzvr";
       }
-    else if stdenv.system == "i686-linux" then
+    else if stdenv.hostPlatform.system == "i686-linux" then
       fetchurl {
         url = "http://www.baudline.com/baudline_${version}_linux_i686.tar.gz";
         sha256 = "1waip5pmcf5ffcfvn8lf1rvsaq2ab66imrbfqs777scz7k8fhhjb";
       }
     else
-      throw "baudline isn't supported (yet?) on ${stdenv.system}";
+      throw "baudline isn't supported (yet?) on ${stdenv.hostPlatform.system}";
 
   buildInputs = [ makeWrapper ];
 
diff --git a/pkgs/applications/audio/google-musicmanager/default.nix b/pkgs/applications/audio/google-musicmanager/default.nix
index 4cd3010ec3d3..b4fe78dcbfcd 100644
--- a/pkgs/applications/audio/google-musicmanager/default.nix
+++ b/pkgs/applications/audio/google-musicmanager/default.nix
@@ -1,6 +1,6 @@
 { stdenv, fetchurl
 , flac, expat, libidn, qtbase, qtwebkit, libvorbis }:
-assert stdenv.system == "x86_64-linux";
+assert stdenv.hostPlatform.system == "x86_64-linux";
 
 stdenv.mkDerivation rec {
   version = "beta_1.0.467.4929-r0"; # friendly to nix-env version sorting algo
diff --git a/pkgs/applications/audio/renoise/default.nix b/pkgs/applications/audio/renoise/default.nix
index 24a2f1a8a601..cd06fa80f5aa 100644
--- a/pkgs/applications/audio/renoise/default.nix
+++ b/pkgs/applications/audio/renoise/default.nix
@@ -17,7 +17,7 @@ stdenv.mkDerivation rec {
   version = "3.1.0";
 
   src =
-    if stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "x86_64-linux" then
         if builtins.isNull releasePath then
         fetchurl {
           url = "https://files.renoise.com/demo/Renoise_${urlVersion version}_Demo_x86_64.tar.bz2";
@@ -25,7 +25,7 @@ stdenv.mkDerivation rec {
         }
         else
         releasePath
-    else if stdenv.system == "i686-linux" then
+    else if stdenv.hostPlatform.system == "i686-linux" then
         if builtins.isNull releasePath then
         fetchurl {
           url = "http://files.renoise.com/demo/Renoise_${urlVersion version}_Demo_x86.tar.bz2";
diff --git a/pkgs/applications/audio/transcribe/default.nix b/pkgs/applications/audio/transcribe/default.nix
index 5ec5087b9f26..c6d5ebc1627f 100644
--- a/pkgs/applications/audio/transcribe/default.nix
+++ b/pkgs/applications/audio/transcribe/default.nix
@@ -7,12 +7,12 @@ stdenv.mkDerivation rec {
   name = "transcribe-${version}";
   version = "8.40";
 
-  src = if stdenv.system == "i686-linux" then
+  src = if stdenv.hostPlatform.system == "i686-linux" then
     fetchzip {
       url = "https://www.seventhstring.com/xscribe/downlinux32_old/xscsetup.tar.gz";
       sha256 = "1ngidmj9zz8bmv754s5xfsjv7v6xr03vck4kigzq4bpc9b1fdhjq";
     }
-  else if stdenv.system == "x86_64-linux" then
+  else if stdenv.hostPlatform.system == "x86_64-linux" then
     fetchzip {
       url = "https://www.seventhstring.com/xscribe/downlinux64_old/xsc64setup.tar.gz";
       sha256 = "0svzi8svj6zn06gj0hr8mpnhq4416dvb4g5al0gpb1g3paywdaf9";
diff --git a/pkgs/applications/editors/eclipse/build-eclipse.nix b/pkgs/applications/editors/eclipse/build-eclipse.nix
index a26d380ec1df..389608ad8249 100644
--- a/pkgs/applications/editors/eclipse/build-eclipse.nix
+++ b/pkgs/applications/editors/eclipse/build-eclipse.nix
@@ -2,7 +2,7 @@
 , zlib, jdk, glib, gtk3, libXtst, gsettings-desktop-schemas, webkitgtk
 , makeWrapper, ... }:
 
-{ name, src ? builtins.getAttr stdenv.system sources, sources ? null, description }:
+{ name, src ? builtins.getAttr stdenv.hostPlatform.system sources, sources ? null, description }:
 
 stdenv.mkDerivation rec {
   inherit name src;
diff --git a/pkgs/applications/editors/eclipse/default.nix b/pkgs/applications/editors/eclipse/default.nix
index c719c7b2da1a..8d47a551c93e 100644
--- a/pkgs/applications/editors/eclipse/default.nix
+++ b/pkgs/applications/editors/eclipse/default.nix
@@ -27,24 +27,24 @@ rec {
     name = "eclipse-cpp-4.7.0";
     description = "Eclipse IDE for C/C++ Developers, Oxygen release";
     src =
-      if stdenv.system == "x86_64-linux" then
+      if stdenv.hostPlatform.system == "x86_64-linux" then
         fetchurl {
           url = https://www.eclipse.org/downloads/download.php?r=1&nf=1&file=/technology/epp/downloads/release/oxygen/R/eclipse-cpp-oxygen-R-linux-gtk-x86_64.tar.gz;
           sha512 = "813c791e739d7d0e2ab242a5bacadca135bbeee20ef97aa830353cd90f63fa6e9c89cfcc6aadf635c742befe035bd6e3f15103013f63c419f6144e86ebde3ed1";
         }
-      else if stdenv.system == "i686-linux" then
+      else if stdenv.hostPlatform.system == "i686-linux" then
         fetchurl {
           url = https://www.eclipse.org/downloads/download.php?r=1&nf=1&file=/technology/epp/downloads/release/oxygen/R/eclipse-cpp-oxygen-R-linux-gtk.tar.gz;
           sha512 = "2b50f4a00306a89cda1aaaa606e62285cacbf93464a9dd3f3319dca3e2c578b802e685de6f78e5e617d269e21271188effe73d41f491a6de946e28795d82db8a";
         }
-      else throw "Unsupported system: ${stdenv.system}";
+      else throw "Unsupported system: ${stdenv.hostPlatform.system}";
   };
 
   eclipse-cpp-37 = buildEclipse {
     name = "eclipse-cpp-3.7";
     description = "Eclipse IDE for C/C++ Developers";
     src =
-      if stdenv.system == "x86_64-linux" then
+      if stdenv.hostPlatform.system == "x86_64-linux" then
         fetchurl {
           url = https://www.eclipse.org/downloads/download.php?r=1&nf=1&file=/technology/epp/downloads/release/indigo/R/eclipse-cpp-indigo-incubation-linux-gtk-x86_64.tar.gz;
           sha256 = "14ppc9g9igzvj1pq7jl01vwhzb66nmzbl9wsdl1sf3xnwa9wnqk3";
@@ -65,7 +65,7 @@ rec {
     name = "eclipse-modeling-4.7";
     description = "Eclipse Modeling Tools";
     src =
-      if stdenv.system == "x86_64-linux" then
+      if stdenv.hostPlatform.system == "x86_64-linux" then
         fetchurl {
           url = https://www.eclipse.org/downloads/download.php?r=1&nf=1&file=/technology/epp/downloads/release/oxygen/R/eclipse-modeling-oxygen-R-linux-gtk-x86_64.tar.gz;
           sha512 = "3b9a7ad4b5d6b77fbdd64e8d323e0adb6c2904763ad042b374b4d87cef8607408cb407e395870fc755d58c0c800e20818adcf456ebe193d76cede16c5fe12271";
@@ -81,7 +81,7 @@ rec {
     name = "eclipse-modeling-3.6.2";
     description = "Eclipse Modeling Tools (includes Incubating components)";
     src =
-      if stdenv.system == "x86_64-linux" then
+      if stdenv.hostPlatform.system == "x86_64-linux" then
         fetchurl {
           url = https://www.eclipse.org/downloads/download.php?r=1&nf=1&file=/technology/epp/downloads/release/helios/SR2/eclipse-modeling-helios-SR2-incubation-linux-gtk-x86_64.tar.gz;
           sha1 = "e96f5f006298f68476f4a15a2be8589158d5cc61";
@@ -151,7 +151,7 @@ rec {
     name = "eclipse-scala-sdk-4.4.1";
     description = "Eclipse IDE for Scala Developers";
     src =
-      if stdenv.system == "x86_64-linux" then
+      if stdenv.hostPlatform.system == "x86_64-linux" then
         fetchurl { # tested
           url = https://downloads.typesafe.com/scalaide-pack/4.4.1-vfinal-luna-211-20160504/scala-SDK-4.4.1-vfinal-2.11-linux.gtk.x86_64.tar.gz;
           sha256  = "4c2d1ac68384e12a11a851cf0fc7757aea087eba69329b21d539382a65340d27";
diff --git a/pkgs/applications/editors/jetbrains/common.nix b/pkgs/applications/editors/jetbrains/common.nix
index 04de4f564c33..2bb84bce0b12 100644
--- a/pkgs/applications/editors/jetbrains/common.nix
+++ b/pkgs/applications/editors/jetbrains/common.nix
@@ -42,7 +42,7 @@ with stdenv; lib.makeOverridable mkDerivation rec {
       }
 
       interpreter=$(echo ${stdenv.glibc.out}/lib/ld-linux*.so.2)
-      if [ "${stdenv.system}" == "x86_64-linux" ]; then
+      if [ "${stdenv.hostPlatform.system}" == "x86_64-linux" ]; then
         target_size=$(get_file_size bin/fsnotifier64)
         patchelf --set-interpreter "$interpreter" bin/fsnotifier64
         munge_size_hack bin/fsnotifier64 $target_size
diff --git a/pkgs/applications/editors/kodestudio/default.nix b/pkgs/applications/editors/kodestudio/default.nix
index 4e22e032e357..b212773712c2 100644
--- a/pkgs/applications/editors/kodestudio/default.nix
+++ b/pkgs/applications/editors/kodestudio/default.nix
@@ -8,15 +8,15 @@ let
 
   version = "17.1";
 
-  sha256 = if stdenv.system == "x86_64-linux"  then "1kddisnvlk48jip6k59mw3wlkrl7rkck2lxpaghn0gfx02cvms5f"
-      else if stdenv.system == "i686-cygwin"   then "1izp42afrlh4yd322ax9w85ki388gnkqfqbw8dwnn4k3j7r5487z"
-      else throw "Unsupported system: ${stdenv.system}";
+  sha256 = if stdenv.hostPlatform.system == "x86_64-linux"  then "1kddisnvlk48jip6k59mw3wlkrl7rkck2lxpaghn0gfx02cvms5f"
+      else if stdenv.hostPlatform.system == "i686-cygwin"   then "1izp42afrlh4yd322ax9w85ki388gnkqfqbw8dwnn4k3j7r5487z"
+      else throw "Unsupported system: ${stdenv.hostPlatform.system}";
 
   urlBase = "https://github.com/Kode/KodeStudio/releases/download/v${version}/KodeStudio-";
 
-  urlStr = if stdenv.system == "x86_64-linux"  then urlBase + "linux64.tar.gz"
-      else if stdenv.system == "i686-cygwin"   then urlBase + "win32.zip"
-      else throw "Unsupported system: ${stdenv.system}";
+  urlStr = if stdenv.hostPlatform.system == "x86_64-linux"  then urlBase + "linux64.tar.gz"
+      else if stdenv.hostPlatform.system == "i686-cygwin"   then urlBase + "win32.zip"
+      else throw "Unsupported system: ${stdenv.hostPlatform.system}";
 
 in
 
@@ -47,7 +47,7 @@ in
       cp -r ./* $out
     '';
 
-    postFixup = lib.optionalString (stdenv.system == "i686-linux" || stdenv.system == "x86_64-linux") ''
+    postFixup = lib.optionalString (stdenv.hostPlatform.system == "i686-linux" || stdenv.hostPlatform.system == "x86_64-linux") ''
       # Patch Binaries
       patchelf \
           --set-interpreter "$(cat $NIX_CC/nix-support/dynamic-linker)" \
diff --git a/pkgs/applications/editors/music/tuxguitar/default.nix b/pkgs/applications/editors/music/tuxguitar/default.nix
index f305db1abb8f..1b1c6eaf9e54 100644
--- a/pkgs/applications/editors/music/tuxguitar/default.nix
+++ b/pkgs/applications/editors/music/tuxguitar/default.nix
@@ -1,7 +1,7 @@
 { stdenv, fetchurl, swt, jdk, makeWrapper, alsaLib }:
 
-let metadata = assert stdenv.system == "i686-linux" || stdenv.system == "x86_64-linux";
-  if stdenv.system == "i686-linux" then
+let metadata = assert stdenv.hostPlatform.system == "i686-linux" || stdenv.hostPlatform.system == "x86_64-linux";
+  if stdenv.hostPlatform.system == "i686-linux" then
     { arch = "x86"; sha256 = "1qmb51k0538pn7gv4nsvhfv33xik4l4af0qmpllkzrikmj8wvzlb"; }
   else
     { arch = "x86_64"; sha256 = "12af47jhlrh9aq5b3d13l7cdhlndgnfpy61gz002hajbq7i00ixh"; };
diff --git a/pkgs/applications/editors/sublime/2/default.nix b/pkgs/applications/editors/sublime/2/default.nix
index 78c2d9aaa0c4..11724d9802a5 100644
--- a/pkgs/applications/editors/sublime/2/default.nix
+++ b/pkgs/applications/editors/sublime/2/default.nix
@@ -6,7 +6,7 @@ in
 stdenv.mkDerivation rec {
   name = "sublimetext-2.0.2";
   src =
-    if stdenv.system == "i686-linux" then
+    if stdenv.hostPlatform.system == "i686-linux" then
       fetchurl {
         name = "sublimetext-2.0.2.tar.bz2";
         url = http://c758482.r82.cf2.rackcdn.com/Sublime%20Text%202.0.2.tar.bz2;
diff --git a/pkgs/applications/editors/sublime/3/common.nix b/pkgs/applications/editors/sublime/3/common.nix
index 628993dbf5be..eb282b1be3a8 100644
--- a/pkgs/applications/editors/sublime/3/common.nix
+++ b/pkgs/applications/editors/sublime/3/common.nix
@@ -13,13 +13,13 @@ let
     ++ stdenv.lib.optional gksuSupport "/usr/bin/gksudo=${gksu}/bin/gksudo";
 in let
   archSha256 =
-    if stdenv.system == "i686-linux" then
+    if stdenv.hostPlatform.system == "i686-linux" then
       x32sha256
     else
       x64sha256;
 
   arch =
-    if stdenv.system == "i686-linux" then
+    if stdenv.hostPlatform.system == "i686-linux" then
       "x32"
     else
       "x64";
diff --git a/pkgs/applications/editors/typora/default.nix b/pkgs/applications/editors/typora/default.nix
index 93ee70e4148b..0bff4864c612 100644
--- a/pkgs/applications/editors/typora/default.nix
+++ b/pkgs/applications/editors/typora/default.nix
@@ -6,7 +6,7 @@ stdenv.mkDerivation rec {
   version = "0.9.53";
 
   src =
-    if stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchurl {
         url = "https://www.typora.io/linux/typora_${version}_amd64.deb";
         sha256 = "02k6x30l4mbjragqbq5rn663xbw3h4bxzgppfxqf5lwydswldklb";
diff --git a/pkgs/applications/editors/vscode/default.nix b/pkgs/applications/editors/vscode/default.nix
index a775fb3bd79a..0cf0c7bcbc69 100644
--- a/pkgs/applications/editors/vscode/default.nix
+++ b/pkgs/applications/editors/vscode/default.nix
@@ -9,15 +9,15 @@ let
     "i686-linux" = "linux-ia32";
     "x86_64-linux" = "linux-x64";
     "x86_64-darwin" = "darwin";
-  }.${stdenv.system};
+  }.${stdenv.hostPlatform.system};
 
   sha256 = {
     "i686-linux" = "1g7kqbz6mrf8ngx2bnwpi9fifq5rjznxgsgwjb532z3nh92ypa8n";
     "x86_64-linux" = "02yldycakn5zxj1ji4nmhdyazqlkjqpzdj3g8j501c3j28pgiwjy";
     "x86_64-darwin" = "0pnsfkh20mj7pzqw7wlfd98jqc6a1mnsq1iira15n7fafqgj8zpl";
-  }.${stdenv.system};
+  }.${stdenv.hostPlatform.system};
 
-  archive_fmt = if stdenv.system == "x86_64-darwin" then "zip" else "tar.gz";
+  archive_fmt = if stdenv.hostPlatform.system == "x86_64-darwin" then "zip" else "tar.gz";
 
   rpath = lib.concatStringsSep ":" [
     atomEnv.libPath
@@ -48,12 +48,12 @@ in
       categories = "GNOME;GTK;Utility;TextEditor;Development;";
     };
 
-    buildInputs = if stdenv.system == "x86_64-darwin"
+    buildInputs = if stdenv.hostPlatform.system == "x86_64-darwin"
       then [ unzip libXScrnSaver libsecret ]
       else [ wrapGAppsHook libXScrnSaver libxkbfile libsecret ];
 
     installPhase =
-      if stdenv.system == "x86_64-darwin" then ''
+      if stdenv.hostPlatform.system == "x86_64-darwin" then ''
         mkdir -p $out/lib/vscode $out/bin
         cp -r ./* $out/lib/vscode
         ln -s $out/lib/vscode/Contents/Resources/app/bin/code $out/bin
@@ -72,7 +72,7 @@ in
         cp $out/lib/vscode/resources/app/resources/linux/code.png $out/share/pixmaps/code.png
       '';
 
-    postFixup = lib.optionalString (stdenv.system == "i686-linux" || stdenv.system == "x86_64-linux") ''
+    postFixup = lib.optionalString (stdenv.hostPlatform.system == "i686-linux" || stdenv.hostPlatform.system == "x86_64-linux") ''
       patchelf \
         --set-interpreter "$(cat $NIX_CC/nix-support/dynamic-linker)" \
         --set-rpath "${rpath}" \
diff --git a/pkgs/applications/graphics/ImageMagick/7.0.nix b/pkgs/applications/graphics/ImageMagick/7.0.nix
index c4afd6b3bed3..893f8d1da6d7 100644
--- a/pkgs/applications/graphics/ImageMagick/7.0.nix
+++ b/pkgs/applications/graphics/ImageMagick/7.0.nix
@@ -7,10 +7,10 @@
 
 let
   arch =
-    if stdenv.system == "i686-linux" then "i686"
-    else if stdenv.system == "x86_64-linux" || stdenv.system == "x86_64-darwin" then "x86-64"
-    else if stdenv.system == "armv7l-linux" then "armv7l"
-    else if stdenv.system == "aarch64-linux" then "aarch64"
+    if stdenv.hostPlatform.system == "i686-linux" then "i686"
+    else if stdenv.hostPlatform.system == "x86_64-linux" || stdenv.hostPlatform.system == "x86_64-darwin" then "x86-64"
+    else if stdenv.hostPlatform.system == "armv7l-linux" then "armv7l"
+    else if stdenv.hostPlatform.system == "aarch64-linux" then "aarch64"
     else throw "ImageMagick is not supported on this platform.";
 
   cfg = {
diff --git a/pkgs/applications/graphics/ImageMagick/default.nix b/pkgs/applications/graphics/ImageMagick/default.nix
index 94a4aeaa9337..22d1341f0dcf 100644
--- a/pkgs/applications/graphics/ImageMagick/default.nix
+++ b/pkgs/applications/graphics/ImageMagick/default.nix
@@ -7,10 +7,10 @@
 
 let
   arch =
-    if stdenv.system == "i686-linux" then "i686"
-    else if stdenv.system == "x86_64-linux" || stdenv.system == "x86_64-darwin" then "x86-64"
-    else if stdenv.system == "armv7l-linux" then "armv7l"
-    else if stdenv.system == "aarch64-linux" then "aarch64"
+    if stdenv.hostPlatform.system == "i686-linux" then "i686"
+    else if stdenv.hostPlatform.system == "x86_64-linux" || stdenv.hostPlatform.system == "x86_64-darwin" then "x86-64"
+    else if stdenv.hostPlatform.system == "armv7l-linux" then "armv7l"
+    else if stdenv.hostPlatform.system == "aarch64-linux" then "aarch64"
     else throw "ImageMagick is not supported on this platform.";
 
   cfg = {
diff --git a/pkgs/applications/graphics/gcolor2/default.nix b/pkgs/applications/graphics/gcolor2/default.nix
index 3747b802e231..27ca6e26e9f9 100644
--- a/pkgs/applications/graphics/gcolor2/default.nix
+++ b/pkgs/applications/graphics/gcolor2/default.nix
@@ -3,7 +3,7 @@
 let version = "0.4"; in
 stdenv.mkDerivation {
   name = "gcolor2-${version}";
-  arch = if stdenv.system == "x86_64-linux" then "amd64" else "386";
+  arch = if stdenv.hostPlatform.system == "x86_64-linux" then "amd64" else "386";
 
   src = fetchurl {
     url = "mirror://sourceforge/project/gcolor2/gcolor2/${version}/gcolor2-${version}.tar.bz2";
@@ -16,7 +16,7 @@ stdenv.mkDerivation {
   '';
 
   # from https://github.com/PhantomX/slackbuilds/tree/master/gcolor2/patches
-  patches = if stdenv.system == "x86_64-linux" then
+  patches = if stdenv.hostPlatform.system == "x86_64-linux" then
         [ ./gcolor2-amd64.patch ] else
         [ ];
 
diff --git a/pkgs/applications/graphics/sane/backends/brscan4/default.nix b/pkgs/applications/graphics/sane/backends/brscan4/default.nix
index df44c132ed96..b431cf51b019 100644
--- a/pkgs/applications/graphics/sane/backends/brscan4/default.nix
+++ b/pkgs/applications/graphics/sane/backends/brscan4/default.nix
@@ -12,17 +12,17 @@ let
 in stdenv.mkDerivation rec {
   name = "brscan4-0.4.4-4";
   src = 
-    if stdenv.system == "i686-linux" then
+    if stdenv.hostPlatform.system == "i686-linux" then
       fetchurl {
         url = "http://download.brother.com/welcome/dlf006646/${name}.i386.deb";
         sha256 = "13mhjbzf9nvpdzrc2s98684r7likg76zxs1wlz2h8w59fsqgx4k2";
       }
-    else if stdenv.system == "x86_64-linux" then
+    else if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchurl {
         url = "https://download.brother.com/welcome/dlf006645/${name}.amd64.deb";
         sha256 = "0xy5px96y1saq9l80vwvfn6anr2q42qlxdhm6ci2a0diwib5q9fd";
       }
-    else throw "${name} is not supported on ${stdenv.system} (only i686-linux and x86_64 linux are supported)";
+    else throw "${name} is not supported on ${stdenv.hostPlatform.system} (only i686-linux and x86_64 linux are supported)";
 
   unpackPhase = ''
     ar x $src
diff --git a/pkgs/applications/graphics/unigine-valley/default.nix b/pkgs/applications/graphics/unigine-valley/default.nix
index f1adc6bd10ea..d29c9cd82598 100644
--- a/pkgs/applications/graphics/unigine-valley/default.nix
+++ b/pkgs/applications/graphics/unigine-valley/default.nix
@@ -17,12 +17,12 @@
 let
   version = "1.0";
 
-  arch = if stdenv.system == "x86_64-linux" then
+  arch = if stdenv.hostPlatform.system == "x86_64-linux" then
     "x64"
-  else if stdenv.system == "i686-linux" then
+  else if stdenv.hostPlatform.system == "i686-linux" then
     "x86"
   else
-    throw "Unsupported platform ${stdenv.system}";
+    throw "Unsupported platform ${stdenv.hostPlatform.system}";
 
 in
   stdenv.mkDerivation rec {
diff --git a/pkgs/applications/misc/1password/default.nix b/pkgs/applications/misc/1password/default.nix
index 94dfc68fb59b..331f516c88ce 100644
--- a/pkgs/applications/misc/1password/default.nix
+++ b/pkgs/applications/misc/1password/default.nix
@@ -4,19 +4,19 @@ stdenv.mkDerivation rec {
   name = "1password-${version}";
   version = "0.5.3";
   src =
-    if stdenv.system == "i686-linux" then
+    if stdenv.hostPlatform.system == "i686-linux" then
       fetchzip {
         url = "https://cache.agilebits.com/dist/1P/op/pkg/v${version}/op_linux_386_v${version}.zip";
         sha256 = "05s223h1yps4k9kmignl0r5sbh6w7m1hnlmafnf1kiwv7gacvxjc";
         stripRoot = false;
       }
-    else if stdenv.system == "x86_64-linux" then
+    else if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchzip {
         url = "https://cache.agilebits.com/dist/1P/op/pkg/v${version}/op_linux_amd64_v${version}.zip";
         sha256 = "0p9x1fx0309v8dxxaf88m8x8q15zzqywfmjn6v5wb9v3scp9396v";
         stripRoot = false;
       }
-    else if stdenv.system == "x86_64-darwin" then
+    else if stdenv.hostPlatform.system == "x86_64-darwin" then
       fetchzip {
         url = "https://cache.agilebits.com/dist/1P/op/pkg/v${version}/op_darwin_amd64_v${version}.zip";
         sha256 = "1z2xp9bn93gr4ha6zx65va1fb58a2xlnnmpv583y96gq3vbnqdcj";
diff --git a/pkgs/applications/misc/adobe-reader/default.nix b/pkgs/applications/misc/adobe-reader/default.nix
index 88bf87b0a84f..0ca12a0096ed 100644
--- a/pkgs/applications/misc/adobe-reader/default.nix
+++ b/pkgs/applications/misc/adobe-reader/default.nix
@@ -1,7 +1,7 @@
 { stdenv, fetchurl, libX11, cups, zlib, libxml2, pango, atk, gtk2, glib
 , gdk_pixbuf }:
 
-assert stdenv.system == "i686-linux";
+assert stdenv.hostPlatform.system == "i686-linux";
 
 let version = "9.5.5"; in
 
diff --git a/pkgs/applications/misc/cura/lulzbot.nix b/pkgs/applications/misc/cura/lulzbot.nix
index 6a36e42eaa3d..f3f1972f6e6e 100644
--- a/pkgs/applications/misc/cura/lulzbot.nix
+++ b/pkgs/applications/misc/cura/lulzbot.nix
@@ -8,17 +8,17 @@ stdenv.mkDerivation rec {
   version = "15.02.1-1.03-5064";
 
   src =
-    if stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchurl {
         url = "https://download.alephobjects.com/ao/aodeb/dists/jessie/main/binary-amd64/cura_${version}_amd64.deb";
         sha256 = "1gsfidg3gim5pjbl82vkh0cw4ya253m4p7nirm8nr6yjrsirkzxg";
       }
-    else if stdenv.system == "i686-linux" then
+    else if stdenv.hostPlatform.system == "i686-linux" then
       fetchurl {
         url = "http://download.alephobjects.com/ao/aodeb/dists/jessie/main/binary-i386/cura_${version}_i386.deb";
         sha256 = "0xd3df6bxq4rijgvsqvps454jkc1nzhxbdzzj6j2w317ppsbhyc1";
       }
-    else throw "${name} is not supported on ${stdenv.system}";
+    else throw "${name} is not supported on ${stdenv.hostPlatform.system}";
 
   python_deps = with py; [ pyopengl pyserial numpy wxPython30 power setuptools ];
   pythonPath = python_deps;
diff --git a/pkgs/applications/misc/googleearth/default.nix b/pkgs/applications/misc/googleearth/default.nix
index 9c1b457c299d..96f8cb116143 100644
--- a/pkgs/applications/misc/googleearth/default.nix
+++ b/pkgs/applications/misc/googleearth/default.nix
@@ -4,9 +4,9 @@
 
 let
   arch =
-    if stdenv.system == "x86_64-linux" then "amd64"
-    else if stdenv.system == "i686-linux" then "i386"
-    else throw "Unsupported system ${stdenv.system}";
+    if stdenv.hostPlatform.system == "x86_64-linux" then "amd64"
+    else if stdenv.hostPlatform.system == "i686-linux" then "i386"
+    else throw "Unsupported system ${stdenv.hostPlatform.system}";
   sha256 =
     if arch == "amd64"
     then "0dwnppn5snl5bwkdrgj4cyylnhngi0g66fn2k41j3dvis83x24k6"
diff --git a/pkgs/applications/misc/icesl/default.nix b/pkgs/applications/misc/icesl/default.nix
index 49b1741fd5af..c0c1faef09d2 100644
--- a/pkgs/applications/misc/icesl/default.nix
+++ b/pkgs/applications/misc/icesl/default.nix
@@ -6,10 +6,10 @@ stdenv.mkDerivation rec {
   name = "iceSL-${version}";
   version = "2.1.10";
 
-  src =  if stdenv.system == "x86_64-linux" then fetchzip {
+  src =  if stdenv.hostPlatform.system == "x86_64-linux" then fetchzip {
     url = "https://gforge.inria.fr/frs/download.php/file/37268/icesl${version}-amd64.zip";
     sha256 = "0dv3mq6wy46xk9blzzmgbdxpsjdaxid3zadfrysxlhmgl7zb2cn2";
-  } else if stdenv.system == "i686-linux" then fetchzip {
+  } else if stdenv.hostPlatform.system == "i686-linux" then fetchzip {
     url = "https://gforge.inria.fr/frs/download.php/file/37267/icesl${version}-i386.zip";
     sha256 = "0sl54fsb2gz6dy0bwdscpdq1ab6ph5b7zald3bwzgkqsvna7p1jr";
   } else throw "Unsupported architecture";
diff --git a/pkgs/applications/misc/kdbplus/default.nix b/pkgs/applications/misc/kdbplus/default.nix
index ba048761367c..b518481e29ad 100644
--- a/pkgs/applications/misc/kdbplus/default.nix
+++ b/pkgs/applications/misc/kdbplus/default.nix
@@ -1,6 +1,6 @@
 { stdenv, requireFile, unzip, rlwrap, bash }:
 
-assert (stdenv.system == "i686-linux");
+assert (stdenv.hostPlatform.system == "i686-linux");
 
 let
   libPath = stdenv.lib.makeLibraryPath
diff --git a/pkgs/applications/misc/kiwix/default.nix b/pkgs/applications/misc/kiwix/default.nix
index c37d26f3dbcc..8d095b78cdbf 100644
--- a/pkgs/applications/misc/kiwix/default.nix
+++ b/pkgs/applications/misc/kiwix/default.nix
@@ -25,7 +25,7 @@ let
     sha256 = "1h9vcbvf8wgds6i2z20y7krpys0mqsqhv1ijyfljanp6vyll9fvi";
   };
 
-  xulrunner = if stdenv.system == "x86_64-linux"
+  xulrunner = if stdenv.hostPlatform.system == "x86_64-linux"
               then { tar = xulrunner64_tar; sdk = xulrunnersdk64_tar; }
               else { tar = xulrunner32_tar; sdk = xulrunnersdk32_tar; };
 
diff --git a/pkgs/applications/misc/playonlinux/default.nix b/pkgs/applications/misc/playonlinux/default.nix
index 2ad6321d5191..8c9f13ce92c7 100644
--- a/pkgs/applications/misc/playonlinux/default.nix
+++ b/pkgs/applications/misc/playonlinux/default.nix
@@ -44,9 +44,9 @@ let
     ];
 
   ld32 =
-    if stdenv.system == "x86_64-linux" then "${stdenv.cc}/nix-support/dynamic-linker-m32"
-    else if stdenv.system == "i686-linux" then "${stdenv.cc}/nix-support/dynamic-linker"
-    else throw "Unsupported platform for PlayOnLinux: ${stdenv.system}";
+    if stdenv.hostPlatform.system == "x86_64-linux" then "${stdenv.cc}/nix-support/dynamic-linker-m32"
+    else if stdenv.hostPlatform.system == "i686-linux" then "${stdenv.cc}/nix-support/dynamic-linker"
+    else throw "Unsupported platform for PlayOnLinux: ${stdenv.hostPlatform.system}";
   ld64 = "${stdenv.cc}/nix-support/dynamic-linker";
   libs = pkgs: stdenv.lib.makeLibraryPath [ pkgs.xorg.libX11 ];
 
@@ -83,7 +83,7 @@ in stdenv.mkDerivation {
 
     bunzip2 $out/share/playonlinux/bin/check_dd_x86.bz2
     patchelf --set-interpreter $(cat ${ld32}) --set-rpath ${libs pkgsi686Linux} $out/share/playonlinux/bin/check_dd_x86
-    ${if stdenv.system == "x86_64-linux" then ''
+    ${if stdenv.hostPlatform.system == "x86_64-linux" then ''
       bunzip2 $out/share/playonlinux/bin/check_dd_amd64.bz2
       patchelf --set-interpreter $(cat ${ld64}) --set-rpath ${libs pkgs} $out/share/playonlinux/bin/check_dd_amd64
     '' else ''
diff --git a/pkgs/applications/misc/rescuetime/default.nix b/pkgs/applications/misc/rescuetime/default.nix
index 57cdfd08d5b0..d9cd85d5098a 100644
--- a/pkgs/applications/misc/rescuetime/default.nix
+++ b/pkgs/applications/misc/rescuetime/default.nix
@@ -2,7 +2,7 @@
 
 let
   src =
-    if stdenv.system == "i686-linux" then fetchurl {
+    if stdenv.hostPlatform.system == "i686-linux" then fetchurl {
       name = "rescuetime-installer.deb";
       url = "https://www.rescuetime.com/installers/rescuetime_current_i386.deb";
       sha256 = "06q1jwqsrjvlj820dd4vl80jznwafsqshsg0p6si8qx4721blryz";
diff --git a/pkgs/applications/misc/sweethome3d/default.nix b/pkgs/applications/misc/sweethome3d/default.nix
index 68a192d78b84..3c56a6a046fb 100644
--- a/pkgs/applications/misc/sweethome3d/default.nix
+++ b/pkgs/applications/misc/sweethome3d/default.nix
@@ -55,7 +55,7 @@ let
 
       makeWrapper ${jre}/bin/java $out/bin/$exec \
         --prefix XDG_DATA_DIRS : "$XDG_ICON_DIRS:${gtk3.out}/share:${gsettings-desktop-schemas}/share:$out/share:$GSETTINGS_SCHEMAS_PATH" \
-        --add-flags "-jar $out/share/java/${module}-${version}.jar -cp $out/share/java/Furniture.jar:$out/share/java/Textures.jar:$out/share/java/Help.jar ${if stdenv.system == "x86_64-linux" then "-d64" else "-d32"}"
+        --add-flags "-jar $out/share/java/${module}-${version}.jar -cp $out/share/java/Furniture.jar:$out/share/java/Textures.jar:$out/share/java/Help.jar -d${toString stdenv.hostPlatform.parsed.cpu.bits}"
     '';
 
     dontStrip = true;
diff --git a/pkgs/applications/misc/sweethome3d/editors.nix b/pkgs/applications/misc/sweethome3d/editors.nix
index 14285a52e27c..eef5185aaeed 100644
--- a/pkgs/applications/misc/sweethome3d/editors.nix
+++ b/pkgs/applications/misc/sweethome3d/editors.nix
@@ -44,7 +44,7 @@ let
       cp "${editorItem}/share/applications/"* $out/share/applications
       makeWrapper ${jre}/bin/java $out/bin/$exec \
         --prefix XDG_DATA_DIRS : "$XDG_ICON_DIRS:${gtk3.out}/share:${gsettings-desktop-schemas}/share:$out/share:$GSETTINGS_SCHEMAS_PATH" \
-        --add-flags "-jar $out/share/java/${module}-${version}.jar ${if stdenv.system == "x86_64-linux" then "-d64" else "-d32"}"
+        --add-flags "-jar $out/share/java/${module}-${version}.jar -d${toString stdenv.hostPlatform.parsed.cpu.bits}"
     '';
 
     dontStrip = true;
diff --git a/pkgs/applications/misc/xmind/default.nix b/pkgs/applications/misc/xmind/default.nix
index a578c53f0e7c..a12f3dc304ba 100644
--- a/pkgs/applications/misc/xmind/default.nix
+++ b/pkgs/applications/misc/xmind/default.nix
@@ -4,13 +4,13 @@ stdenv.mkDerivation rec {
   name = "xmind-${version}";
   version = "7.5-update1";
 
-  src = if stdenv.system == "i686-linux" then fetchurl {
+  src = if stdenv.hostPlatform.system == "i686-linux" then fetchurl {
     url = "http://dl2.xmind.net/xmind-downloads/${name}-linux_i386.deb";
     sha256 = "04kr6pw0kwy715bp9wcnqnw1k5wl65xa87lhljrskm291p402jy1";
-  } else if stdenv.system == "x86_64-linux" then fetchurl {
+  } else if stdenv.hostPlatform.system == "x86_64-linux" then fetchurl {
     url = "http://dl2.xmind.net/xmind-downloads/${name}-linux_amd64.deb";
     sha256 = "1j2ynhk7p3m3vd6c4mjwpnlzqgfj5c4q3zydab3nfwncwx6gaqj9";
-  } else throw "platform ${stdenv.system} not supported!";
+  } else throw "platform ${stdenv.hostPlatform.system} not supported!";
 
   nativeBuildInputs = [ dpkg makeWrapper ];
 
diff --git a/pkgs/applications/networking/apache-directory-studio/default.nix b/pkgs/applications/networking/apache-directory-studio/default.nix
index d593947f3e62..05dee5b6154c 100644
--- a/pkgs/applications/networking/apache-directory-studio/default.nix
+++ b/pkgs/applications/networking/apache-directory-studio/default.nix
@@ -21,17 +21,17 @@ stdenv.mkDerivation rec {
   version = "2.0.0.v20170904-M13";
 
   src =
-    if stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchurl {
         url = "mirror://apache/directory/studio/${version}/ApacheDirectoryStudio-${version}-linux.gtk.x86_64.tar.gz";
         sha256 = "1jfnm6m0ijk31r30hhrxxnizk742dm317iny041p29v897rma7aq";
       }
-    else if stdenv.system == "i686-linux" then
+    else if stdenv.hostPlatform.system == "i686-linux" then
       fetchurl {
         url = "mirror://apache/directory/studio/${version}/ApacheDirectoryStudio-${version}-linux.gtk.x86.tar.gz";
         sha256 = "1bxmgram42qyhrqkgp5k8770f5mjjdd4c6xl4gj09smiycm1qa4n";
       }
-    else throw "Unsupported system: ${stdenv.system}";
+    else throw "Unsupported system: ${stdenv.hostPlatform.system}";
 
   buildInputs = [ makeWrapper ];
 
diff --git a/pkgs/applications/networking/bittorrentsync/generic.nix b/pkgs/applications/networking/bittorrentsync/generic.nix
index dae540ba4260..1075aea8db3a 100644
--- a/pkgs/applications/networking/bittorrentsync/generic.nix
+++ b/pkgs/applications/networking/bittorrentsync/generic.nix
@@ -4,9 +4,9 @@ let
   arch = {
     "x86_64-linux" = "x64";
     "i686-linux" = "i386";
-  }.${stdenv.system} or throwSystem;
+  }.${stdenv.hostPlatform.system} or throwSystem;
   libPath = stdenv.lib.makeLibraryPath [ stdenv.cc.libc ];
-  throwSystem = throw "Unsupported system: ${stdenv.system}";
+  throwSystem = throw "Unsupported system: ${stdenv.hostPlatform.system}";
 in
 
 stdenv.mkDerivation rec {
@@ -20,7 +20,7 @@ stdenv.mkDerivation rec {
       "https://download-cdn.getsync.com/${version}/linux-${arch}/BitTorrent-Sync_${arch}.tar.gz"
       "http://syncapp.bittorrent.com/${version}/btsync_${arch}-${version}.tar.gz"
     ];
-    sha256 = sha256s.${stdenv.system} or throwSystem;
+    sha256 = sha256s.${stdenv.hostPlatform.system} or throwSystem;
   };
 
   dontStrip = true; # Don't strip, otherwise patching the rpaths breaks
diff --git a/pkgs/applications/networking/browsers/firefox-bin/default.nix b/pkgs/applications/networking/browsers/firefox-bin/default.nix
index 1fbcb3d97143..7e92df163afc 100644
--- a/pkgs/applications/networking/browsers/firefox-bin/default.nix
+++ b/pkgs/applications/networking/browsers/firefox-bin/default.nix
@@ -59,7 +59,7 @@ let
     "x86_64-linux" = "linux-x86_64";
   };
 
-  arch = mozillaPlatforms.${stdenv.system};
+  arch = mozillaPlatforms.${stdenv.hostPlatform.system};
 
   isPrefixOf = prefix: string:
     builtins.substring 0 (builtins.stringLength prefix) string == prefix;
diff --git a/pkgs/applications/networking/browsers/firefox/wrapper.nix b/pkgs/applications/networking/browsers/firefox/wrapper.nix
index b64a6cf7ad98..8b06c35fe005 100644
--- a/pkgs/applications/networking/browsers/firefox/wrapper.nix
+++ b/pkgs/applications/networking/browsers/firefox/wrapper.nix
@@ -36,10 +36,10 @@ let
       jre = cfg.jre or false;
       icedtea = cfg.icedtea or false;
       supportsJDK =
-        stdenv.system == "i686-linux" ||
-        stdenv.system == "x86_64-linux" ||
-        stdenv.system == "armv7l-linux" ||
-        stdenv.system == "aarch64-linux";
+        stdenv.hostPlatform.system == "i686-linux" ||
+        stdenv.hostPlatform.system == "x86_64-linux" ||
+        stdenv.hostPlatform.system == "armv7l-linux" ||
+        stdenv.hostPlatform.system == "aarch64-linux";
 
       plugins =
         assert !(jre && icedtea);
diff --git a/pkgs/applications/networking/browsers/mozilla-plugins/flashplayer/default.nix b/pkgs/applications/networking/browsers/mozilla-plugins/flashplayer/default.nix
index 94d0e9e5badd..72e1a08f40b3 100644
--- a/pkgs/applications/networking/browsers/mozilla-plugins/flashplayer/default.nix
+++ b/pkgs/applications/networking/browsers/mozilla-plugins/flashplayer/default.nix
@@ -60,13 +60,13 @@
 
 let
   arch =
-    if stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "x86_64-linux" then
       "x86_64"
-    else if stdenv.system == "i686-linux"   then
+    else if stdenv.hostPlatform.system == "i686-linux"   then
       "i386"
     else throw "Flash Player is not supported on this platform";
   lib_suffix =
-      if stdenv.system == "x86_64-linux" then
+      if stdenv.hostPlatform.system == "x86_64-linux" then
       "64"
     else
       "";
diff --git a/pkgs/applications/networking/browsers/mozilla-plugins/google-talk-plugin/default.nix b/pkgs/applications/networking/browsers/mozilla-plugins/google-talk-plugin/default.nix
index a172e0e8d5d9..71b5161c1e39 100644
--- a/pkgs/applications/networking/browsers/mozilla-plugins/google-talk-plugin/default.nix
+++ b/pkgs/applications/networking/browsers/mozilla-plugins/google-talk-plugin/default.nix
@@ -54,12 +54,12 @@ stdenv.mkDerivation rec {
   version = "5.41.3.0";
 
   src =
-    if stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchurl {
         url = "${baseURL}/google-talkplugin_${version}-1_amd64.deb";
         sha1 = "0bbc3d6997ba22ce712d93e5bc336c894b54fc81";
       }
-    else if stdenv.system == "i686-linux" then
+    else if stdenv.hostPlatform.system == "i686-linux" then
       fetchurl {
         url = "${baseURL}/google-talkplugin_${version}-1_i386.deb";
         sha1 = "6eae0544858f85c68b0cc46d7786e990bd94f139";
diff --git a/pkgs/applications/networking/browsers/mozilla-plugins/trezor/default.nix b/pkgs/applications/networking/browsers/mozilla-plugins/trezor/default.nix
index 3d4e0fc00225..5f7f601b3545 100644
--- a/pkgs/applications/networking/browsers/mozilla-plugins/trezor/default.nix
+++ b/pkgs/applications/networking/browsers/mozilla-plugins/trezor/default.nix
@@ -8,7 +8,7 @@ stdenv.mkDerivation {
   };
 
   src =
-    if stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchurl {
         url    = https://mytrezor.com/data/plugin/1.0.5/browser-plugin-trezor_1.0.5_amd64.deb;
         sha256 = "0097h4v88yca4aayzprrh4pk03xvvj7ncz2mi83chm81gsr2v67z";
diff --git a/pkgs/applications/networking/browsers/tor-browser-bundle-bin/default.nix b/pkgs/applications/networking/browsers/tor-browser-bundle-bin/default.nix
index de6766709131..f5f88cdfc027 100644
--- a/pkgs/applications/networking/browsers/tor-browser-bundle-bin/default.nix
+++ b/pkgs/applications/networking/browsers/tor-browser-bundle-bin/default.nix
@@ -125,7 +125,7 @@ stdenv.mkDerivation rec {
   name = "tor-browser-bundle-bin-${version}";
   inherit version;
 
-  src = srcs."${stdenv.system}" or (throw "unsupported system: ${stdenv.system}");
+  src = srcs."${stdenv.hostPlatform.system}" or (throw "unsupported system: ${stdenv.hostPlatform.system}");
 
   preferLocalBuild = true;
   allowSubstitutes = false;
diff --git a/pkgs/applications/networking/dropbox/default.nix b/pkgs/applications/networking/dropbox/default.nix
index 3450ad720486..047ad734bd40 100644
--- a/pkgs/applications/networking/dropbox/default.nix
+++ b/pkgs/applications/networking/dropbox/default.nix
@@ -2,7 +2,7 @@
 
 let platforms = [ "i686-linux" "x86_64-linux" ]; in
 
-assert lib.elem stdenv.system platforms;
+assert lib.elem stdenv.hostPlatform.system platforms;
 
 # Dropbox client to bootstrap installation.
 # The client is self-updating, so the actual version may be newer.
@@ -12,7 +12,7 @@ let
   arch = {
     "x86_64-linux" = "x86_64";
     "i686-linux"   = "x86";
-  }.${stdenv.system};
+  }.${stdenv.hostPlatform.system};
 
   installer = "https://clientupdates.dropboxstatic.com/dbx-releng/client/dropbox-lnx.${arch}-${version}.tar.gz";
 in
diff --git a/pkgs/applications/networking/instant-messengers/franz/default.nix b/pkgs/applications/networking/instant-messengers/franz/default.nix
index b253e41ae7d8..2f3870d78994 100644
--- a/pkgs/applications/networking/instant-messengers/franz/default.nix
+++ b/pkgs/applications/networking/instant-messengers/franz/default.nix
@@ -3,7 +3,7 @@
 , gnome2, dbus, nss, nspr, alsaLib, cups, expat, udev, libnotify, xdg_utils }:
 
 let
-  bits = if stdenv.system == "x86_64-linux" then "x64"
+  bits = if stdenv.hostPlatform.system == "x86_64-linux" then "x64"
          else "ia32";
 
   version = "4.0.4";
diff --git a/pkgs/applications/networking/instant-messengers/mattermost-desktop/default.nix b/pkgs/applications/networking/instant-messengers/mattermost-desktop/default.nix
index a9ce8a96f970..109893850de1 100644
--- a/pkgs/applications/networking/instant-messengers/mattermost-desktop/default.nix
+++ b/pkgs/applications/networking/instant-messengers/mattermost-desktop/default.nix
@@ -41,18 +41,18 @@ in
     version = "4.1.2";
 
     src =
-      if stdenv.system == "x86_64-linux" then
+      if stdenv.hostPlatform.system == "x86_64-linux" then
         fetchurl {
           url = "https://releases.mattermost.com/desktop/${version}/${name}-linux-x64.tar.gz";
           sha256 = "16dn6870bs1nfl2082ym9gwvmqb3i5sli48qprap80p7riph6k9s";
         }
-      else if stdenv.system == "i686-linux" then
+      else if stdenv.hostPlatform.system == "i686-linux" then
         fetchurl {
           url = "https://releases.mattermost.com/desktop/${version}/${name}-linux-ia32.tar.gz";
           sha256 = "145zb1l37fa2slfrrlprlwzcc5km3plxs374yhgix25mlg2afkqr";
         }
       else
-        throw "Mattermost-Desktop is not currently supported on ${stdenv.system}";
+        throw "Mattermost-Desktop is not currently supported on ${stdenv.hostPlatform.system}";
 
     phases = [ "unpackPhase" "installPhase" ];
     installPhase = ''
diff --git a/pkgs/applications/networking/instant-messengers/rambox/sencha/bare.nix b/pkgs/applications/networking/instant-messengers/rambox/sencha/bare.nix
index ca82f30e2d1f..af92462a2a49 100644
--- a/pkgs/applications/networking/instant-messengers/rambox/sencha/bare.nix
+++ b/pkgs/applications/networking/instant-messengers/rambox/sencha/bare.nix
@@ -18,7 +18,7 @@ stdenv.mkDerivation rec {
   inherit version;
 
   name = "sencha-bare-${version}";
-  src = srcs.${stdenv.system};
+  src = srcs.${stdenv.hostPlatform.system};
 
   nativeBuildInputs = [ gzip which unzip ];
   buildInputs = [ jdk ];
diff --git a/pkgs/applications/networking/instant-messengers/skypeforlinux/default.nix b/pkgs/applications/networking/instant-messengers/skypeforlinux/default.nix
index d728c8d95cca..eaa9103a7b64 100644
--- a/pkgs/applications/networking/instant-messengers/skypeforlinux/default.nix
+++ b/pkgs/applications/networking/instant-messengers/skypeforlinux/default.nix
@@ -53,13 +53,13 @@ let
   ] + ":${stdenv.cc.cc.lib}/lib64";
 
   src =
-    if stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchurl {
         url = "https://repo.skype.com/deb/pool/main/s/skypeforlinux/skypeforlinux_${version}_amd64.deb";
         sha256 = "1kydf71qbz35dx4674h3nxfx8a88k620217906i54ic4qq2mgy2x";
       }
     else
-      throw "Skype for linux is not supported on ${stdenv.system}";
+      throw "Skype for linux is not supported on ${stdenv.hostPlatform.system}";
 
 in stdenv.mkDerivation {
   name = "skypeforlinux-${version}";
diff --git a/pkgs/applications/networking/instant-messengers/slack/default.nix b/pkgs/applications/networking/instant-messengers/slack/default.nix
index bcf887808750..af2030a20b8a 100644
--- a/pkgs/applications/networking/instant-messengers/slack/default.nix
+++ b/pkgs/applications/networking/instant-messengers/slack/default.nix
@@ -44,13 +44,13 @@ let
   ] + ":${stdenv.cc.cc.lib}/lib64";
 
   src =
-    if stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchurl {
         url = "https://downloads.slack-edge.com/linux_releases/slack-desktop-${version}-amd64.deb";
         sha256 = "095dpkwvvnwlxsglyg6wi9126wpalzi736b6g6j3bd6d93z9afah";
       }
     else
-      throw "Slack is not supported on ${stdenv.system}";
+      throw "Slack is not supported on ${stdenv.hostPlatform.system}";
 
 in stdenv.mkDerivation {
   name = "slack-${version}";
diff --git a/pkgs/applications/networking/instant-messengers/wire-desktop/default.nix b/pkgs/applications/networking/instant-messengers/wire-desktop/default.nix
index 0745836271ae..0985f139238e 100644
--- a/pkgs/applications/networking/instant-messengers/wire-desktop/default.nix
+++ b/pkgs/applications/networking/instant-messengers/wire-desktop/default.nix
@@ -44,12 +44,12 @@ let
   plat = {
     "i686-linux" = "i386";
     "x86_64-linux" = "amd64";
-  }.${stdenv.system};
+  }.${stdenv.hostPlatform.system};
 
   sha256 = {
     "i686-linux" = "071ddh2d8wmiybwafwyb97962zj358l0fq7g2r44231653sgybvq";
     "x86_64-linux" = "0qp9ms94smnm7k47b0n0jdzvnm1b7gj25hyinsfc6lghrb6jqw3r";
-  }.${stdenv.system};
+  }.${stdenv.hostPlatform.system};
 
 in
   stdenv.mkDerivation rec {
diff --git a/pkgs/applications/networking/instant-messengers/zoom-us/default.nix b/pkgs/applications/networking/instant-messengers/zoom-us/default.nix
index afc6f03edb4a..882215c50c5c 100644
--- a/pkgs/applications/networking/instant-messengers/zoom-us/default.nix
+++ b/pkgs/applications/networking/instant-messengers/zoom-us/default.nix
@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, system, makeWrapper, makeDesktopItem, autoPatchelfHook, env
+{ stdenv, fetchurl, makeWrapper, makeDesktopItem, autoPatchelfHook, env
 # Dynamic libraries
 , dbus, glib, libGL, libX11, libXfixes, libuuid, libxcb, qtbase, qtdeclarative
 , qtimageformats, qtlocation, qtquickcontrols, qtquickcontrols2, qtscript, qtsvg
@@ -31,7 +31,7 @@ let
 in stdenv.mkDerivation {
   name = "zoom-us-${version}";
 
-  src = srcs.${system};
+  src = srcs.${stdenv.hostPlatform.system};
 
   nativeBuildInputs = [ autoPatchelfHook makeWrapper ];
 
diff --git a/pkgs/applications/networking/insync/default.nix b/pkgs/applications/networking/insync/default.nix
index e718dc6562fb..fee19de0e8d7 100644
--- a/pkgs/applications/networking/insync/default.nix
+++ b/pkgs/applications/networking/insync/default.nix
@@ -4,13 +4,13 @@ stdenv.mkDerivation rec {
   name = "insync-${version}";
   version = "1.4.5.37069";
   src =
-    if stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchurl {
         url = "http://s.insynchq.com/builds/insync-portable_${version}_amd64.tar.bz2";
         sha256 = "0mkqgpq4isngkj20c0ygmxf4cj975d446svhwvl3cqdrjkjm1ybd";
       }
     else
-      throw "${name} is not supported on ${stdenv.system}";
+      throw "${name} is not supported on ${stdenv.hostPlatform.system}";
 
   buildInputs = [ makeWrapper ];
 
diff --git a/pkgs/applications/networking/mailreaders/nylas-mail-bin/default.nix b/pkgs/applications/networking/mailreaders/nylas-mail-bin/default.nix
index 3376eebe5dc9..3d8673a87a1b 100644
--- a/pkgs/applications/networking/mailreaders/nylas-mail-bin/default.nix
+++ b/pkgs/applications/networking/mailreaders/nylas-mail-bin/default.nix
@@ -33,13 +33,13 @@ stdenv.mkDerivation rec {
   subVersion = "fec7941";
 
   src =
-    if stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchurl {
         url = "https://edgehill.s3.amazonaws.com/${version}-${subVersion}/linux-deb/x64/NylasMail.deb";
         sha256 = "40060aa1dc3b5187b8ed4a07b9de3427e3c5a291df98c2c82395647fa2aa4ada";
       }
     else
-      throw "NylasMail is not supported on ${stdenv.system}";
+      throw "NylasMail is not supported on ${stdenv.hostPlatform.system}";
 
   propagatedBuildInputs = [
     alsaLib
diff --git a/pkgs/applications/networking/mailreaders/thunderbird-bin/default.nix b/pkgs/applications/networking/mailreaders/thunderbird-bin/default.nix
index b9b553f94472..cf68a2686194 100644
--- a/pkgs/applications/networking/mailreaders/thunderbird-bin/default.nix
+++ b/pkgs/applications/networking/mailreaders/thunderbird-bin/default.nix
@@ -47,7 +47,7 @@
 with (import ./release_sources.nix);
 
 let
-  arch = if stdenv.system == "i686-linux"
+  arch = if stdenv.hostPlatform.system == "i686-linux"
     then "linux-i686"
     else "linux-x86_64";
 
diff --git a/pkgs/applications/networking/p2p/frostwire/default.nix b/pkgs/applications/networking/p2p/frostwire/default.nix
index 7b854fce6c55..40ff91e792b4 100644
--- a/pkgs/applications/networking/p2p/frostwire/default.nix
+++ b/pkgs/applications/networking/p2p/frostwire/default.nix
@@ -75,7 +75,7 @@ in stdenv.mkDerivation {
     cp ${ { x86_64-darwin = "desktop/lib/native/*.dylib";
             x86_64-linux  = "desktop/lib/native/lib{jlibtorrent,SystemUtilities}.so";
             i686-linux    = "desktop/lib/native/lib{jlibtorrent,SystemUtilities}X86.so";
-          }.${stdenv.system} or (throw "unsupported system ${stdenv.system}")
+          }.${stdenv.hostPlatform.system} or (throw "unsupported system ${stdenv.hostPlatform.system}")
         } $out/lib
 
     cp -dpR ${desktopItem}/share $out
diff --git a/pkgs/applications/networking/p2p/soulseekqt/default.nix b/pkgs/applications/networking/p2p/soulseekqt/default.nix
index 44e434aa8ee9..12ed680482f6 100644
--- a/pkgs/applications/networking/p2p/soulseekqt/default.nix
+++ b/pkgs/applications/networking/p2p/soulseekqt/default.nix
@@ -37,7 +37,7 @@ in stdenv.mkDerivation rec {
 
   name = "soulseekqt-${version}";
   inherit version;
-  src = srcs."${stdenv.system}" or (throw "unsupported system: ${stdenv.system}");
+  src = srcs."${stdenv.hostPlatform.system}" or (throw "unsupported system: ${stdenv.hostPlatform.system}");
 
   dontBuild = true;
 
diff --git a/pkgs/applications/networking/remote/anydesk/default.nix b/pkgs/applications/networking/remote/anydesk/default.nix
index 0f107936be6f..cb3814b55f19 100644
--- a/pkgs/applications/networking/remote/anydesk/default.nix
+++ b/pkgs/applications/networking/remote/anydesk/default.nix
@@ -6,12 +6,12 @@ let
   sha256 = {
     "x86_64-linux" = "0g19sac4j3m1nf400vn6qcww7prqg2p4k4zsj74i109kk1396aa2";
     "i686-linux"   = "1dd4ai2pclav9g872xil3x67bxy32gvz9pb3w76383pcsdh5zh45";
-  }."${stdenv.system}" or (throw "system ${stdenv.system} not supported");
+  }."${stdenv.hostPlatform.system}" or (throw "system ${stdenv.hostPlatform.system} not supported");
 
   arch = {
     "x86_64-linux" = "amd64";
     "i686-linux"   = "i686";
-  }."${stdenv.system}" or (throw "system ${stdenv.system} not supported");
+  }."${stdenv.hostPlatform.system}" or (throw "system ${stdenv.hostPlatform.system} not supported");
 
   description = "Desktop sharing application, providing remote support and online meetings";
 
diff --git a/pkgs/applications/networking/resilio-sync/default.nix b/pkgs/applications/networking/resilio-sync/default.nix
index 0db18e77bfa6..b59219d99366 100644
--- a/pkgs/applications/networking/resilio-sync/default.nix
+++ b/pkgs/applications/networking/resilio-sync/default.nix
@@ -4,7 +4,7 @@ let
   arch = {
     "x86_64-linux" = "x64";
     "i686-linux" = "i386";
-  }.${stdenv.system} or (throw "Unsupported system: ${stdenv.system}");
+  }.${stdenv.hostPlatform.system} or (throw "Unsupported system: ${stdenv.hostPlatform.system}");
   libPath = stdenv.lib.makeLibraryPath [ stdenv.cc.libc ];
 
 in stdenv.mkDerivation rec {
@@ -16,7 +16,7 @@ in stdenv.mkDerivation rec {
     sha256 = {
       "x86_64-linux" = "0041axi9carspkfaxvyirfvsa29zz55al01x90nh93nzxvpvywsz";
       "i686-linux"   = "1ar36lp4f6a1z9i82g3gpak4q4ny09faqxdd59q1pvfzq25ypdhs";
-    }.${stdenv.system};
+    }.${stdenv.hostPlatform.system};
   };
 
   dontStrip = true; # Don't strip, otherwise patching the rpaths breaks
diff --git a/pkgs/applications/networking/spideroak/default.nix b/pkgs/applications/networking/spideroak/default.nix
index c1f3d62af737..c07ad715afd2 100644
--- a/pkgs/applications/networking/spideroak/default.nix
+++ b/pkgs/applications/networking/spideroak/default.nix
@@ -4,17 +4,17 @@
 }:
 
 let
-  arch = if stdenv.system == "x86_64-linux" then "x64"
-    else if stdenv.system == "i686-linux" then "x86"
-    else throw "Spideroak client for: ${stdenv.system} not supported!";
+  arch = if stdenv.hostPlatform.system == "x86_64-linux" then "x64"
+    else if stdenv.hostPlatform.system == "i686-linux" then "x86"
+    else throw "Spideroak client for: ${stdenv.hostPlatform.system} not supported!";
 
-  interpreter = if stdenv.system == "x86_64-linux" then "ld-linux-x86-64.so.2"
-    else if stdenv.system == "i686-linux" then "ld-linux.so.2"
-    else throw "Spideroak client for: ${stdenv.system} not supported!";
+  interpreter = if stdenv.hostPlatform.system == "x86_64-linux" then "ld-linux-x86-64.so.2"
+    else if stdenv.hostPlatform.system == "i686-linux" then "ld-linux.so.2"
+    else throw "Spideroak client for: ${stdenv.hostPlatform.system} not supported!";
 
-  sha256 = if stdenv.system == "x86_64-linux" then "a88e5a8fe4a565ac500668bd53cf5784752d7c9253304ddce39ee7b01d078533"
-    else if stdenv.system == "i686-linux" then "668f3b83a974a3877d16c8743c233a427ea0a44ab84b7f9aec19a2995db66c16"
-    else throw "Spideroak client for: ${stdenv.system} not supported!";
+  sha256 = if stdenv.hostPlatform.system == "x86_64-linux" then "a88e5a8fe4a565ac500668bd53cf5784752d7c9253304ddce39ee7b01d078533"
+    else if stdenv.hostPlatform.system == "i686-linux" then "668f3b83a974a3877d16c8743c233a427ea0a44ab84b7f9aec19a2995db66c16"
+    else throw "Spideroak client for: ${stdenv.hostPlatform.system} not supported!";
 
   ldpath = stdenv.lib.makeLibraryPath [
     fontconfig freetype glib libICE libSM
diff --git a/pkgs/applications/networking/super-productivity/default.nix b/pkgs/applications/networking/super-productivity/default.nix
index 59872afaad93..9bb4254c64a2 100644
--- a/pkgs/applications/networking/super-productivity/default.nix
+++ b/pkgs/applications/networking/super-productivity/default.nix
@@ -44,13 +44,13 @@ let
   ] + ":${stdenv.cc.cc.lib}/lib64";
 
   src =
-    if stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchurl {
         url = "https://github.com/johannesjo/super-productivity/releases/download/v${version}/superProductivity_${version}_amd64.deb";
         sha256 = "0jfi0lfijnhij9jvkhxgyvq8m1jzaym8n1c7707fv3hjh1h0vxn1";
       }
     else
-      throw "super-productivity is not supported on ${stdenv.system}";
+      throw "super-productivity is not supported on ${stdenv.hostPlatform.system}";
 
 in stdenv.mkDerivation {
   name = "super-productivity-${version}";
diff --git a/pkgs/applications/office/jameica/default.nix b/pkgs/applications/office/jameica/default.nix
index fdc6c58213a1..8d17ef2acaa4 100644
--- a/pkgs/applications/office/jameica/default.nix
+++ b/pkgs/applications/office/jameica/default.nix
@@ -6,10 +6,10 @@ let
   version = "${_version}-${_build}";
   name = "jameica-${version}";
 
-  swtSystem = if stdenv.system == "i686-linux" then "linux"
-  else if stdenv.system == "x86_64-linux" then "linux64"
-  else if stdenv.system == "x86_64-darwin" then "macos64"
-  else throw "Unsupported system: ${stdenv.system}";
+  swtSystem = if stdenv.hostPlatform.system == "i686-linux" then "linux"
+  else if stdenv.hostPlatform.system == "x86_64-linux" then "linux64"
+  else if stdenv.hostPlatform.system == "x86_64-darwin" then "macos64"
+  else throw "Unsupported system: ${stdenv.hostPlatform.system}";
 
   desktopItem = makeDesktopItem {
     name = "jameica";
diff --git a/pkgs/applications/office/mendeley/default.nix b/pkgs/applications/office/mendeley/default.nix
index 693fa63661b5..5b6271db83bd 100644
--- a/pkgs/applications/office/mendeley/default.nix
+++ b/pkgs/applications/office/mendeley/default.nix
@@ -37,7 +37,7 @@
 let
   arch32 = "i686-linux";
 
-  arch = if stdenv.system == arch32
+  arch = if stdenv.hostPlatform.system == arch32
     then "i386"
     else "amd64";
 
@@ -46,7 +46,7 @@ let
   version = "${shortVersion}_${arch}";
 
   url = "http://desktop-download.mendeley.com/download/apt/pool/main/m/mendeleydesktop/mendeleydesktop_${version}.deb";
-  sha256 = if stdenv.system == arch32
+  sha256 = if stdenv.hostPlatform.system == arch32
     then "0fcyl5i8xdgb5j0x1643qc0j74d8p11jczvqmgqkqh0wgid1y1ad"
     else "1dzwa2cnn9xakrhhq159fhh71gw5wlbf017rrikdlia694m8akq6";
 
diff --git a/pkgs/applications/office/moneyplex/default.nix b/pkgs/applications/office/moneyplex/default.nix
index 47d2ecc81ea3..9f4ed80e6d80 100644
--- a/pkgs/applications/office/moneyplex/default.nix
+++ b/pkgs/applications/office/moneyplex/default.nix
@@ -21,8 +21,8 @@ stdenv.mkDerivation rec {
   name = "moneyplex-${version}";
   version = "16.0.22424";
 
-  src = fetchurl (if stdenv.system == "i686-linux" then src_i686
-                  else if stdenv.system == "x86_64-linux" then src_x86_64
+  src = fetchurl (if stdenv.hostPlatform.system == "i686-linux" then src_i686
+                  else if stdenv.hostPlatform.system == "x86_64-linux" then src_x86_64
                   else throw "moneyplex requires i686-linux or x86_64-linux");
 
 
diff --git a/pkgs/applications/office/wpsoffice/default.nix b/pkgs/applications/office/wpsoffice/default.nix
index 46faf9ba651e..4c83d67f7cda 100644
--- a/pkgs/applications/office/wpsoffice/default.nix
+++ b/pkgs/applications/office/wpsoffice/default.nix
@@ -3,7 +3,7 @@
 , zlib, libpng12, libICE, libXrender, cups }:
 
 let
-  bits = if stdenv.system == "x86_64-linux" then "x86_64"
+  bits = if stdenv.hostPlatform.system == "x86_64-linux" then "x86_64"
          else "x86";
 
   version = "10.1.0.5672";
diff --git a/pkgs/applications/science/electronics/eagle/eagle7.nix b/pkgs/applications/science/electronics/eagle/eagle7.nix
index 9b8827187b26..d5720440f7cc 100644
--- a/pkgs/applications/science/electronics/eagle/eagle7.nix
+++ b/pkgs/applications/science/electronics/eagle/eagle7.nix
@@ -17,18 +17,18 @@ stdenv.mkDerivation rec {
   version = "7.7.0";
 
   src =
-    if stdenv.system == "i686-linux" then
+    if stdenv.hostPlatform.system == "i686-linux" then
       fetchurl {
         url = "ftp://ftp.cadsoft.de/eagle/program/7.7/eagle-lin32-${version}.run";
         sha256 = "16fa66p77xigc7zvzfm7737mllrcs6nrgk2p7wvkjw3p9lvbz7z1";
       }
-    else if stdenv.system == "x86_64-linux" then
+    else if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchurl {
         url = "ftp://ftp.cadsoft.de/eagle/program/7.7/eagle-lin64-${version}.run";
         sha256 = "18dcn6wqph1sqh0ah98qzfi05wip8a8ifbkaq79iskbrsi8iqnrg";
       }
     else
-      throw "Unsupported system: ${stdenv.system}";
+      throw "Unsupported system: ${stdenv.hostPlatform.system}";
 
   desktopItem = makeDesktopItem {
     name = "eagle";
diff --git a/pkgs/applications/science/logic/isabelle/default.nix b/pkgs/applications/science/logic/isabelle/default.nix
index ae04c11d9590..ffe508569553 100644
--- a/pkgs/applications/science/logic/isabelle/default.nix
+++ b/pkgs/applications/science/logic/isabelle/default.nix
@@ -48,7 +48,7 @@ stdenv.mkDerivation {
       rm -rf $comp/x86*
     done
     '' + (if ! stdenv.isLinux then "" else ''
-    arch=${if stdenv.system == "x86_64-linux" then "x86_64-linux" else "x86-linux"}
+    arch=${if stdenv.hostPlatform.system == "x86_64-linux" then "x86_64-linux" else "x86-linux"}
     for f in contrib/*/$arch/{bash_process,epclextract,eprover,nunchaku,SPASS}; do
       patchelf --set-interpreter $(cat ${stdenv.cc}/nix-support/dynamic-linker) "$f"
     done
diff --git a/pkgs/applications/science/logic/saw-tools/default.nix b/pkgs/applications/science/logic/saw-tools/default.nix
index 65d2b4d91c30..32ebdad51d94 100644
--- a/pkgs/applications/science/logic/saw-tools/default.nix
+++ b/pkgs/applications/science/logic/saw-tools/default.nix
@@ -12,7 +12,7 @@ let
   url = "https://github.com/GaloisInc/saw-script/releases/download";
 
   saw-bin =
-    if stdenv.system == "i686-linux"
+    if stdenv.hostPlatform.system == "i686-linux"
     then fetchurl {
       url    = url + "/v0.1.1-dev/saw-0.1.1-dev-2015-07-31-CentOS6-32.tar.gz";
       sha256 = "126iag5nnvndi78c921z7vjrjfwcspn1hlxwwhzmqm4rvbhhr9v9";
diff --git a/pkgs/applications/science/math/mathematica/10.nix b/pkgs/applications/science/math/mathematica/10.nix
index 4884ee1f93ab..c6802c3719e9 100644
--- a/pkgs/applications/science/math/mathematica/10.nix
+++ b/pkgs/applications/science/math/mathematica/10.nix
@@ -18,7 +18,7 @@
 
 let
   platform =
-    if stdenv.system == "i686-linux" || stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "i686-linux" || stdenv.hostPlatform.system == "x86_64-linux" then
       "Linux"
     else
       throw "Mathematica requires i686-linux or x86_64 linux";
@@ -70,7 +70,7 @@ stdenv.mkDerivation rec {
   ]);
 
   ldpath = stdenv.lib.makeLibraryPath buildInputs
-    + stdenv.lib.optionalString (stdenv.system == "x86_64-linux")
+    + stdenv.lib.optionalString (stdenv.hostPlatform.system == "x86_64-linux")
       (":" + stdenv.lib.makeSearchPathOutput "lib" "lib64" buildInputs);
 
   phases = "unpackPhase installPhase fixupPhase";
diff --git a/pkgs/applications/science/math/mathematica/9.nix b/pkgs/applications/science/math/mathematica/9.nix
index d60feb54695d..1023e7ca3d5c 100644
--- a/pkgs/applications/science/math/mathematica/9.nix
+++ b/pkgs/applications/science/math/mathematica/9.nix
@@ -16,7 +16,7 @@
 
 let
   platform =
-    if stdenv.system == "i686-linux" || stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "i686-linux" || stdenv.hostPlatform.system == "x86_64-linux" then
       "Linux"
     else
       throw "Mathematica requires i686-linux or x86_64 linux";
@@ -60,7 +60,7 @@ stdenv.mkDerivation rec {
   ]);
 
   ldpath = stdenv.lib.makeLibraryPath buildInputs
-    + stdenv.lib.optionalString (stdenv.system == "x86_64-linux")
+    + stdenv.lib.optionalString (stdenv.hostPlatform.system == "x86_64-linux")
       (":" + stdenv.lib.makeSearchPathOutput "lib" "lib64" buildInputs);
 
   phases = "unpackPhase installPhase fixupPhase";
diff --git a/pkgs/applications/science/math/mathematica/default.nix b/pkgs/applications/science/math/mathematica/default.nix
index fa4ff8b00687..165a56605579 100644
--- a/pkgs/applications/science/math/mathematica/default.nix
+++ b/pkgs/applications/science/math/mathematica/default.nix
@@ -69,7 +69,7 @@ stdenv.mkDerivation rec {
   ]);
 
   ldpath = stdenv.lib.makeLibraryPath buildInputs
-    + stdenv.lib.optionalString (stdenv.system == "x86_64-linux")
+    + stdenv.lib.optionalString (stdenv.hostPlatform.system == "x86_64-linux")
       (":" + stdenv.lib.makeSearchPathOutput "lib" "lib64" buildInputs);
 
   phases = "unpackPhase installPhase fixupPhase";
diff --git a/pkgs/applications/science/math/scilab-bin/default.nix b/pkgs/applications/science/math/scilab-bin/default.nix
index dacd3e730736..54b262fe5058 100644
--- a/pkgs/applications/science/math/scilab-bin/default.nix
+++ b/pkgs/applications/science/math/scilab-bin/default.nix
@@ -10,9 +10,9 @@ let
   badArch = throw "${name} requires i686-linux or x86_64-linux";
 
   architecture =
-    if stdenv.system == "i686-linux" then
+    if stdenv.hostPlatform.system == "i686-linux" then
       "i686"
-    else if stdenv.system == "x86_64-linux" then
+    else if stdenv.hostPlatform.system == "x86_64-linux" then
       "x86_64"
     else
       badArch;
@@ -23,9 +23,9 @@ stdenv.mkDerivation rec {
   src = fetchurl {
     url = "https://www.scilab.org/download/${ver}/scilab-${ver}.bin.linux-${architecture}.tar.gz";
     sha256 =
-      if stdenv.system == "i686-linux" then
+      if stdenv.hostPlatform.system == "i686-linux" then
         "0fgjc2ak3b2qi6yin3fy50qwk2bcj0zbz1h4lyyic9n1n1qcliib"
-      else if stdenv.system == "x86_64-linux" then
+      else if stdenv.hostPlatform.system == "x86_64-linux" then
         "1scswlznc14vyzg0gqa1q9gcpwx05kz1sbn563463mzkdp7nd35d"
       else
         badArch;
diff --git a/pkgs/applications/search/recoll/default.nix b/pkgs/applications/search/recoll/default.nix
index 01a4f4023023..e56284ac5c53 100644
--- a/pkgs/applications/search/recoll/default.nix
+++ b/pkgs/applications/search/recoll/default.nix
@@ -5,7 +5,7 @@
 , ghostscript, gawk, gnugrep, gnused, gnutar, gzip, libiconv, zlib
 , withGui ? true }:
 
-assert stdenv.system != "powerpc-linux";
+assert stdenv.hostPlatform.system != "powerpc-linux";
 
 stdenv.mkDerivation rec {
   ver = "1.23.7";
diff --git a/pkgs/applications/video/lightworks/default.nix b/pkgs/applications/video/lightworks/default.nix
index 64a967001b57..4bfd9e790070 100644
--- a/pkgs/applications/video/lightworks/default.nix
+++ b/pkgs/applications/video/lightworks/default.nix
@@ -23,12 +23,12 @@ let
     name = "lightworks-${version}";
     
     src =
-      if stdenv.system == "x86_64-linux" then
+      if stdenv.hostPlatform.system == "x86_64-linux" then
         fetchurl {
           url = "http://downloads.lwks.com/v14/lwks-14.0.0-amd64.deb";
           sha256 = "66eb9f9678d979db76199f1c99a71df0ddc017bb47dfda976b508849ab305033";
         }
-      else throw "${name} is not supported on ${stdenv.system}";
+      else throw "${name} is not supported on ${stdenv.hostPlatform.system}";
 
     buildInputs = [ dpkg makeWrapper ];
 
diff --git a/pkgs/applications/video/mplayer/default.nix b/pkgs/applications/video/mplayer/default.nix
index 02a0c2c0ec49..e017e7cc0015 100644
--- a/pkgs/applications/video/mplayer/default.nix
+++ b/pkgs/applications/video/mplayer/default.nix
@@ -60,13 +60,13 @@ let
     let
       dir = http://www.mplayerhq.hu/MPlayer/releases/codecs/;
     in
-    if stdenv.system == "i686-linux" then fetchurl {
+    if stdenv.hostPlatform.system == "i686-linux" then fetchurl {
       url = "${dir}/essential-20071007.tar.bz2";
       sha256 = "18vls12n12rjw0mzw4pkp9vpcfmd1c21rzha19d7zil4hn7fs2ic";
-    } else if stdenv.system == "x86_64-linux" then fetchurl {
+    } else if stdenv.hostPlatform.system == "x86_64-linux" then fetchurl {
       url = "${dir}/essential-amd64-20071007.tar.bz2";
       sha256 = "13xf5b92w1ra5hw00ck151lypbmnylrnznq9hhb0sj36z5wz290x";
-    } else if stdenv.system == "powerpc-linux" then fetchurl {
+    } else if stdenv.hostPlatform.system == "powerpc-linux" then fetchurl {
       url = "${dir}/essential-ppc-20071007.tar.bz2";
       sha256 = "18mlj8dp4wnz42xbhdk1jlz2ygra6fbln9wyrcyvynxh96g1871z";
     } else null;
diff --git a/pkgs/applications/video/webtorrent_desktop/default.nix b/pkgs/applications/video/webtorrent_desktop/default.nix
index c99aed0c1afb..086190000ab4 100644
--- a/pkgs/applications/video/webtorrent_desktop/default.nix
+++ b/pkgs/applications/video/webtorrent_desktop/default.nix
@@ -42,13 +42,13 @@
     version = "0.20.0";
 
     src =
-      if stdenv.system == "x86_64-linux" then
+      if stdenv.hostPlatform.system == "x86_64-linux" then
         fetchurl {
           url = "https://github.com/webtorrent/webtorrent-desktop/releases/download/v0.20.0/webtorrent-desktop_${version}-1_amd64.deb";
           sha256 = "1kkrnbimiip5pn2nwpln35bbdda9gc3cgrjwphq4fqasbjf2781k";
         }
         else
-          throw "Webtorrent is not currently supported on ${stdenv.system}";
+          throw "Webtorrent is not currently supported on ${stdenv.hostPlatform.system}";
     phases = [ "unpackPhase" "installPhase" ];
     nativeBuildInputs = [ dpkg ];
     unpackPhase = "dpkg-deb -x $src .";
diff --git a/pkgs/applications/virtualization/qemu/default.nix b/pkgs/applications/virtualization/qemu/default.nix
index f9058ef89b65..bbb2a099666b 100644
--- a/pkgs/applications/virtualization/qemu/default.nix
+++ b/pkgs/applications/virtualization/qemu/default.nix
@@ -22,7 +22,7 @@
 
 with stdenv.lib;
 let
-  audio = optionalString (hasSuffix "linux" stdenv.system) "alsa,"
+  audio = optionalString (hasSuffix "linux" stdenv.hostPlatform.system) "alsa,"
     + optionalString pulseSupport "pa,"
     + optionalString sdlSupport "sdl,";
 
diff --git a/pkgs/applications/virtualization/virtualbox/guest-additions/default.nix b/pkgs/applications/virtualization/virtualbox/guest-additions/default.nix
index dcc58b04c8e3..cb7bcad3592d 100644
--- a/pkgs/applications/virtualization/virtualbox/guest-additions/default.nix
+++ b/pkgs/applications/virtualization/virtualbox/guest-additions/default.nix
@@ -44,23 +44,23 @@ stdenv.mkDerivation {
   '';
 
   buildCommand = with xorg; ''
-    ${if stdenv.system == "i686-linux" || stdenv.system == "x86_64-linux" then ''
+    ${if stdenv.hostPlatform.system == "i686-linux" || stdenv.hostPlatform.system == "x86_64-linux" then ''
         isoinfo -J -i $src -x /VBoxLinuxAdditions.run > ./VBoxLinuxAdditions.run
         chmod 755 ./VBoxLinuxAdditions.run
         ./VBoxLinuxAdditions.run --noexec --keep
       ''
-      else throw ("Architecture: "+stdenv.system+" not supported for VirtualBox guest additions")
+      else throw ("Architecture: "+stdenv.hostPlatform.system+" not supported for VirtualBox guest additions")
     }
 
     # Unpack files
     cd install
-    ${if stdenv.system == "i686-linux" then ''
+    ${if stdenv.hostPlatform.system == "i686-linux" then ''
         tar xfvj VBoxGuestAdditions-x86.tar.bz2
       ''
-      else if stdenv.system == "x86_64-linux" then ''
+      else if stdenv.hostPlatform.system == "x86_64-linux" then ''
         tar xfvj VBoxGuestAdditions-amd64.tar.bz2
       ''
-      else throw ("Architecture: "+stdenv.system+" not supported for VirtualBox guest additions")
+      else throw ("Architecture: "+stdenv.hostPlatform.system+" not supported for VirtualBox guest additions")
     }
 
     cd ../
@@ -81,13 +81,13 @@ stdenv.mkDerivation {
     # Change the interpreter for various binaries
     for i in sbin/VBoxService bin/{VBoxClient,VBoxControl} other/mount.vboxsf
     do
-        ${if stdenv.system == "i686-linux" then ''
+        ${if stdenv.hostPlatform.system == "i686-linux" then ''
           patchelf --set-interpreter ${stdenv.glibc.out}/lib/ld-linux.so.2 $i
         ''
-        else if stdenv.system == "x86_64-linux" then ''
+        else if stdenv.hostPlatform.system == "x86_64-linux" then ''
           patchelf --set-interpreter ${stdenv.glibc.out}/lib/ld-linux-x86-64.so.2 $i
         ''
-        else throw ("Architecture: "+stdenv.system+" not supported for VirtualBox guest additions")
+        else throw ("Architecture: "+stdenv.hostPlatform.system+" not supported for VirtualBox guest additions")
         }
         patchelf --set-rpath ${lib.makeLibraryPath [ stdenv.cc.cc dbus libX11 libXt libXext libXmu libXfixes libXrandr libXcursor ]} $i
     done
diff --git a/pkgs/applications/window-managers/i3/default.nix b/pkgs/applications/window-managers/i3/default.nix
index 513fe06df8f6..5c95b9daf251 100644
--- a/pkgs/applications/window-managers/i3/default.nix
+++ b/pkgs/applications/window-managers/i3/default.nix
@@ -36,9 +36,9 @@ stdenv.mkDerivation rec {
   # they shouldn't, and then even once that's fixed have some
   # perl-related errors later on. For more, see
   # https://github.com/NixOS/nixpkgs/issues/7957
-  doCheck = false; # stdenv.system == "x86_64-linux";
+  doCheck = false; # stdenv.hostPlatform.system == "x86_64-linux";
 
-  checkPhase = stdenv.lib.optionalString (stdenv.system == "x86_64-linux")
+  checkPhase = stdenv.lib.optionalString (stdenv.hostPlatform.system == "x86_64-linux")
   ''
     (cd testcases && xvfb-run ./complete-run.pl -p 1 --keep-xserver-output)
     ! grep -q '^not ok' testcases/latest/complete-run.log
diff --git a/pkgs/build-support/build-fhs-userenv/env.nix b/pkgs/build-support/build-fhs-userenv/env.nix
index d951fb9ab06e..23568f51b23e 100644
--- a/pkgs/build-support/build-fhs-userenv/env.nix
+++ b/pkgs/build-support/build-fhs-userenv/env.nix
@@ -1,4 +1,4 @@
-{ stdenv, buildEnv, writeText, pkgs, pkgsi686Linux, system }:
+{ stdenv, buildEnv, writeText, pkgs, pkgsi686Linux }:
 
 { name, profile ? ""
 , targetPkgs ? pkgs: [], multiPkgs ? pkgs: []
@@ -22,7 +22,7 @@
 # /lib will link to /lib32
 
 let
-  is64Bit = system == "x86_64-linux";
+  is64Bit = stdenv.hostPlatform.parsed.cpu.bits == 64;
   isMultiBuild  = multiPkgs != null && is64Bit;
   isTargetBuild = !isMultiBuild;
 
diff --git a/pkgs/build-support/release/nix-build.nix b/pkgs/build-support/release/nix-build.nix
index d42538c7e5d5..feda54de46fe 100644
--- a/pkgs/build-support/release/nix-build.nix
+++ b/pkgs/build-support/release/nix-build.nix
@@ -148,7 +148,7 @@ stdenv.mkDerivation (
     postPhases = postPhases ++ ["finalPhase"];
 
     meta = (if args ? meta then args.meta else {}) // {
-      description = if doCoverageAnalysis then "Coverage analysis" else "Nix package for ${stdenv.system}";
+      description = if doCoverageAnalysis then "Coverage analysis" else "Nix package for ${stdenv.hostPlatform.system}";
     };
 
   }
diff --git a/pkgs/build-support/vm/windows/controller/default.nix b/pkgs/build-support/vm/windows/controller/default.nix
index 17803a28330f..e000308bed8f 100644
--- a/pkgs/build-support/vm/windows/controller/default.nix
+++ b/pkgs/build-support/vm/windows/controller/default.nix
@@ -157,7 +157,7 @@ let
     "-net vde,vlan=0,sock=$QEMU_VDE_SOCKET"
   ]);
 
-  maybeKvm64 = optional (stdenv.system == "x86_64-linux") "-cpu kvm64";
+  maybeKvm64 = optional (stdenv.hostPlatform.system == "x86_64-linux") "-cpu kvm64";
 
   cygwinQemuArgs = concatStringsSep " " (maybeKvm64 ++ [
     "-monitor unix:$MONITOR_SOCKET,server,nowait"
diff --git a/pkgs/build-support/vm/windows/cygwin-iso/default.nix b/pkgs/build-support/vm/windows/cygwin-iso/default.nix
index 2c46d5fae907..76cd41a75bc7 100644
--- a/pkgs/build-support/vm/windows/cygwin-iso/default.nix
+++ b/pkgs/build-support/vm/windows/cygwin-iso/default.nix
@@ -17,7 +17,7 @@ let
   };
 
   cygwinCross = (import ../../../../.. {
-    inherit (stdenv) system;
+    localSystem = stdenv.hostPlatform;
     crossSystem = {
       libc = "msvcrt";
       platform = {};
diff --git a/pkgs/development/arduino/arduino-core/default.nix b/pkgs/development/arduino/arduino-core/default.nix
index a427023df56e..269df6a07cd0 100644
--- a/pkgs/development/arduino/arduino-core/default.nix
+++ b/pkgs/development/arduino/arduino-core/default.nix
@@ -13,15 +13,19 @@ assert withTeensyduino -> withGui;
 # xdotool script; the cause of this hang is not yet known.
 # TODO: There is a fair chance that Teensyduino works with arm-linux, but it
 # has not yet been tested.
-if withTeensyduino && (stdenv.system != "x86_64-linux") then throw
+if withTeensyduino && (stdenv.hostPlatform.system != "x86_64-linux") then throw
   "Teensyduino is only supported on x86_64-linux at this time (patches welcome)."
 else
 let
-  externalDownloads = import ./downloads.nix {inherit fetchurl; inherit (lib) optionalAttrs; inherit (stdenv) system;};
+  externalDownloads = import ./downloads.nix {
+    inherit fetchurl;
+    inherit (lib) optionalAttrs;
+    inherit (stdenv.hostPlatform) system;
+  };
   # Some .so-files are later copied from .jar-s to $HOME, so patch them beforehand
   patchelfInJars =
-       lib.optional (stdenv.system == "x86_64-linux") {jar = "share/arduino/lib/jssc-2.8.0-arduino1.jar"; file = "libs/linux/libjSSC-2.8_x86_64.so";}
-    ++ lib.optional (stdenv.system == "i686-linux") {jar = "share/arduino/lib/jssc-2.8.0-arduino1.jar"; file = "libs/linux/libjSSC-2.8_x86.so";}
+       lib.optional (stdenv.hostPlatform.system == "x86_64-linux") {jar = "share/arduino/lib/jssc-2.8.0-arduino1.jar"; file = "libs/linux/libjSSC-2.8_x86_64.so";}
+    ++ lib.optional (stdenv.hostPlatform.system == "i686-linux") {jar = "share/arduino/lib/jssc-2.8.0-arduino1.jar"; file = "libs/linux/libjSSC-2.8_x86.so";}
   ;
   # abiVersion 6 is default, but we need 5 for `avrdude_bin` executable
   ncurses5 = ncurses.override { abiVersion = "5"; };
@@ -46,9 +50,9 @@ let
     zlib
   ];
   teensy_architecture =
-      lib.optionalString (stdenv.system == "x86_64-linux") "linux64"
-      + lib.optionalString (stdenv.system == "i686-linux") "linux32"
-      + lib.optionalString (stdenv.system == "arm-linux") "linuxarm";
+      lib.optionalString (stdenv.hostPlatform.system == "x86_64-linux") "linux64"
+      + lib.optionalString (stdenv.hostPlatform.system == "i686-linux") "linux32"
+      + lib.optionalString (stdenv.hostPlatform.system == "arm-linux") "linuxarm";
 
   flavor = (if withTeensyduino then "teensyduino" else "arduino")
              + stdenv.lib.optionalString (!withGui) "-core";
diff --git a/pkgs/development/compilers/ccl/default.nix b/pkgs/development/compilers/ccl/default.nix
index 9570b0eead85..ae6af8dd4b4f 100644
--- a/pkgs/development/compilers/ccl/default.nix
+++ b/pkgs/development/compilers/ccl/default.nix
@@ -29,7 +29,7 @@ let
     };
     armv6l-linux = armv7l-linux;
   };
-  cfg = options."${stdenv.system}" or (throw "missing source url for platform ${stdenv.system}");
+  cfg = options."${stdenv.hostPlatform.system}" or (throw "missing source url for platform ${stdenv.hostPlatform.system}");
 in
 
 stdenv.mkDerivation rec {
diff --git a/pkgs/development/compilers/clean/default.nix b/pkgs/development/compilers/clean/default.nix
index 16ac8b787219..cc6197922fd3 100644
--- a/pkgs/development/compilers/clean/default.nix
+++ b/pkgs/development/compilers/clean/default.nix
@@ -4,11 +4,11 @@ stdenv.mkDerivation rec {
   name = "clean-2.4";
 
   src =
-    if stdenv.system == "i686-linux" then (fetchurl {
+    if stdenv.hostPlatform.system == "i686-linux" then (fetchurl {
       url = "http://clean.cs.ru.nl/download/Clean24/linux/clean2.4_boot.tar.gz";
       sha256 = "1w8vvmkwzq8g51639r62apcy75sj69nm08082a34xvqm9ymfgkq5";
     })
-    else if stdenv.system == "x86_64-linux" then (fetchurl {
+    else if stdenv.hostPlatform.system == "x86_64-linux" then (fetchurl {
         url = "https://clean.cs.ru.nl/download/Clean24/linux/clean2.4_64_boot.tar.gz";
         sha256 = "08gsa1pjl5wyzh4ah8ccfx8a7mdcn6ycsn1lzkrr9adygv1gmm7r";
     })
diff --git a/pkgs/development/compilers/cmucl/binary.nix b/pkgs/development/compilers/cmucl/binary.nix
index 2833c5378c1d..9e3184c42eb2 100644
--- a/pkgs/development/compilers/cmucl/binary.nix
+++ b/pkgs/development/compilers/cmucl/binary.nix
@@ -1,7 +1,7 @@
 {stdenv, fetchurl}:
 
 let
-  inherit (stdenv) system;
+  inherit (stdenv.hostPlatform) system;
   version = "21b";
   downloadUrl = arch:
     "http://common-lisp.net/project/cmucl/downloads/release/" +
diff --git a/pkgs/development/compilers/crystal/default.nix b/pkgs/development/compilers/crystal/default.nix
index ce487c3c0e25..aa1c85ebcb00 100644
--- a/pkgs/development/compilers/crystal/default.nix
+++ b/pkgs/development/compilers/crystal/default.nix
@@ -15,14 +15,14 @@ stdenv.mkDerivation rec {
     "x86_64-linux" = "linux-x86_64";
     "i686-linux" = "linux-i686";
     "x86_64-darwin" = "darwin-x86_64";
-  }."${stdenv.system}" or (throw "system ${stdenv.system} not supported");
+  }."${stdenv.hostPlatform.system}" or (throw "system ${stdenv.hostPlatform.system} not supported");
   in fetchurl {
     url = "https://github.com/crystal-lang/crystal/releases/download/0.26.0/${prebuiltName}-${arch}.tar.gz";
     sha256 = {
       "x86_64-linux" = "1xban102yiiwmlklxvn3xp3q546bp8hlxxpakayajkhhnpl6yv45";
       "i686-linux" = "1igspf1lrv7wpmz0pfrkbx8m1ykvnv4zhic53cav4nicppm2v0ic";
       "x86_64-darwin" = "0hzc65ccajr0yhmvi5vbdgbzbp1gbjy56da24ds3zwwkam1ddk0k";
-    }."${stdenv.system}";
+    }."${stdenv.hostPlatform.system}";
   };
 
   unpackPhase = ''
diff --git a/pkgs/development/compilers/fpc/binary.nix b/pkgs/development/compilers/fpc/binary.nix
index 0ecf4437c9a2..cf13ab6f5954 100644
--- a/pkgs/development/compilers/fpc/binary.nix
+++ b/pkgs/development/compilers/fpc/binary.nix
@@ -4,17 +4,17 @@ stdenv.mkDerivation {
   name = "fpc-2.6.0-binary";
 
   src =
-    if stdenv.system == "i686-linux" then
+    if stdenv.hostPlatform.system == "i686-linux" then
       fetchurl {
         url = "mirror://sourceforge/project/freepascal/Linux/2.6.0/fpc-2.6.0.i386-linux.tar";
         sha256 = "08yklvrfxvk59bxsd4rh1i6s3cjn0q06dzjs94h9fbq3n1qd5zdf";
       }
-    else if stdenv.system == "x86_64-linux" then
+    else if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchurl {
         url = "mirror://sourceforge/project/freepascal/Linux/2.6.0/fpc-2.6.0.x86_64-linux.tar";
         sha256 = "0k9vi75k39y735fng4jc2vppdywp82j4qhzn7x4r6qjkad64d8lx";
       }
-    else throw "Not supported on ${stdenv.system}.";
+    else throw "Not supported on ${stdenv.hostPlatform.system}.";
 
   builder = ./binary-builder.sh;
 
diff --git a/pkgs/development/compilers/fpc/default.nix b/pkgs/development/compilers/fpc/default.nix
index 51544783d8c6..b516019ffc9a 100644
--- a/pkgs/development/compilers/fpc/default.nix
+++ b/pkgs/development/compilers/fpc/default.nix
@@ -14,7 +14,7 @@ stdenv.mkDerivation rec {
   buildInputs = [ startFPC gawk ];
 
   preConfigure =
-    if stdenv.system == "i686-linux" || stdenv.system == "x86_64-linux" then ''
+    if stdenv.hostPlatform.system == "i686-linux" || stdenv.hostPlatform.system == "x86_64-linux" then ''
       sed -e "s@'/lib/ld-linux[^']*'@'''@" -i fpcsrc/compiler/systems/t_linux.pas
       sed -e "s@'/lib64/ld-linux[^']*'@'''@" -i fpcsrc/compiler/systems/t_linux.pas
     '' else "";
diff --git a/pkgs/development/compilers/ghcjs-ng/default.nix b/pkgs/development/compilers/ghcjs-ng/default.nix
index ddabb7ca6bfc..5db2777c8bb0 100644
--- a/pkgs/development/compilers/ghcjs-ng/default.nix
+++ b/pkgs/development/compilers/ghcjs-ng/default.nix
@@ -59,7 +59,7 @@ let
   };
 
   bootGhcjs = haskellLib.justStaticExecutables passthru.bootPkgs.ghcjs;
-  libexec = "${bootGhcjs}/libexec/${builtins.replaceStrings ["darwin" "i686"] ["osx" "i386"] stdenv.system}-${passthru.bootPkgs.ghc.name}/${bootGhcjs.name}";
+  libexec = "${bootGhcjs}/libexec/${builtins.replaceStrings ["darwin" "i686"] ["osx" "i386"] stdenv.buildPlatform.system}-${passthru.bootPkgs.ghc.name}/${bootGhcjs.name}";
 
 in stdenv.mkDerivation {
     name = bootGhcjs.name;
diff --git a/pkgs/development/compilers/go/1.10.nix b/pkgs/development/compilers/go/1.10.nix
index 513d0307f6bf..fa4b4abafdee 100644
--- a/pkgs/development/compilers/go/1.10.nix
+++ b/pkgs/development/compilers/go/1.10.nix
@@ -134,12 +134,12 @@ stdenv.mkDerivation rec {
 
   GOOS = if stdenv.isDarwin then "darwin" else "linux";
   GOARCH = if stdenv.isDarwin then "amd64"
-           else if stdenv.system == "i686-linux" then "386"
-           else if stdenv.system == "x86_64-linux" then "amd64"
+           else if stdenv.hostPlatform.system == "i686-linux" then "386"
+           else if stdenv.hostPlatform.system == "x86_64-linux" then "amd64"
            else if stdenv.isAarch32 then "arm"
            else if stdenv.isAarch64 then "arm64"
            else throw "Unsupported system";
-  GOARM = optionalString (stdenv.system == "armv5tel-linux") "5";
+  GOARM = optionalString (stdenv.hostPlatform.system == "armv5tel-linux") "5";
   GO386 = 387; # from Arch: don't assume sse2 on i686
   CGO_ENABLED = 1;
   GOROOT_BOOTSTRAP = "${goBootstrap}/share/go";
diff --git a/pkgs/development/compilers/go/1.11.nix b/pkgs/development/compilers/go/1.11.nix
index eddd16dc1997..55cc654b0aa9 100644
--- a/pkgs/development/compilers/go/1.11.nix
+++ b/pkgs/development/compilers/go/1.11.nix
@@ -134,12 +134,12 @@ stdenv.mkDerivation rec {
 
   GOOS = if stdenv.isDarwin then "darwin" else "linux";
   GOARCH = if stdenv.isDarwin then "amd64"
-           else if stdenv.system == "i686-linux" then "386"
-           else if stdenv.system == "x86_64-linux" then "amd64"
-           else if stdenv.isAarch32 then "arm"
-           else if stdenv.isAarch64 then "arm64"
+           else if stdenv.targetPlatform.isi686 then "386"
+           else if stdenv.targetPlatform.isx86_64 then "amd64"
+           else if stdenv.targetPlatform.isAarch32 then "arm"
+           else if stdenv.targetPlatform.isAarch64 then "arm64"
            else throw "Unsupported system";
-  GOARM = optionalString (stdenv.system == "armv5tel-linux") "5";
+  GOARM = stdenv.targetPlatform.parsed.cpu.version or "";
   GO386 = 387; # from Arch: don't assume sse2 on i686
   CGO_ENABLED = 1;
   GOROOT_BOOTSTRAP = "${goBootstrap}/share/go";
diff --git a/pkgs/development/compilers/go/1.4.nix b/pkgs/development/compilers/go/1.4.nix
index 32eb0d98d188..40fd3f15786b 100644
--- a/pkgs/development/compilers/go/1.4.nix
+++ b/pkgs/development/compilers/go/1.4.nix
@@ -128,11 +128,11 @@ stdenv.mkDerivation rec {
 
   GOOS = if stdenv.isDarwin then "darwin" else "linux";
   GOARCH = if stdenv.isDarwin then "amd64"
-           else if stdenv.system == "i686-linux" then "386"
-           else if stdenv.system == "x86_64-linux" then "amd64"
+           else if stdenv.hostPlatform.system == "i686-linux" then "386"
+           else if stdenv.hostPlatform.system == "x86_64-linux" then "amd64"
            else if stdenv.isAarch32 then "arm"
            else throw "Unsupported system";
-  GOARM = stdenv.lib.optionalString (stdenv.system == "armv5tel-linux") "5";
+  GOARM = stdenv.lib.optionalString (stdenv.hostPlatform.system == "armv5tel-linux") "5";
   GO386 = 387; # from Arch: don't assume sse2 on i686
   CGO_ENABLED = 0;
 
diff --git a/pkgs/development/compilers/go/1.9.nix b/pkgs/development/compilers/go/1.9.nix
index d46e40f460b1..48f16c3ffa5a 100644
--- a/pkgs/development/compilers/go/1.9.nix
+++ b/pkgs/development/compilers/go/1.9.nix
@@ -134,12 +134,12 @@ stdenv.mkDerivation rec {
 
   GOOS = if stdenv.isDarwin then "darwin" else "linux";
   GOARCH = if stdenv.isDarwin then "amd64"
-           else if stdenv.system == "i686-linux" then "386"
-           else if stdenv.system == "x86_64-linux" then "amd64"
+           else if stdenv.hostPlatform.system == "i686-linux" then "386"
+           else if stdenv.hostPlatform.system == "x86_64-linux" then "amd64"
            else if stdenv.isAarch32 then "arm"
            else if stdenv.isAarch64 then "arm64"
            else throw "Unsupported system";
-  GOARM = optionalString (stdenv.system == "armv5tel-linux") "5";
+  GOARM = optionalString (stdenv.hostPlatform.system == "armv5tel-linux") "5";
   GO386 = 387; # from Arch: don't assume sse2 on i686
   CGO_ENABLED = 1;
   GOROOT_BOOTSTRAP = "${goBootstrap}/share/go";
diff --git a/pkgs/development/compilers/jetbrains-jdk/default.nix b/pkgs/development/compilers/jetbrains-jdk/default.nix
index 1c62f79f907b..39fab8b25d8f 100644
--- a/pkgs/development/compilers/jetbrains-jdk/default.nix
+++ b/pkgs/development/compilers/jetbrains-jdk/default.nix
@@ -10,13 +10,13 @@ let drv = stdenv.mkDerivation rec {
   version = "152b1248.6";
   name = pname + "-" + version;
 
-  src = if stdenv.system == "x86_64-linux" then
+  src = if stdenv.hostPlatform.system == "x86_64-linux" then
     fetchurl {
       url = "https://bintray.com/jetbrains/intellij-jdk/download_file?file_path=jbsdk8u${version}_linux_x64.tar.gz";
       sha256 = "12l81g8zhaymh4rzyfl9nyzmpkgzc7wrphm3j4plxx129yn9i7d7";
     }
   else
-    throw "unsupported system: ${stdenv.system}";
+    throw "unsupported system: ${stdenv.hostPlatform.system}";
 
   nativeBuildInputs = [ file ];
 
diff --git a/pkgs/development/compilers/julia/default.nix b/pkgs/development/compilers/julia/default.nix
index 84fdf8f9786d..086570f5ce20 100644
--- a/pkgs/development/compilers/julia/default.nix
+++ b/pkgs/development/compilers/julia/default.nix
@@ -101,7 +101,7 @@ stdenv.mkDerivation rec {
 
   makeFlags =
     let
-      arch = head (splitString "-" stdenv.system);
+      arch = head (splitString "-" stdenv.hostPlatform.system);
       march = { "x86_64" = "x86-64"; "i686" = "pentium4"; }."${arch}"
               or (throw "unsupported architecture: ${arch}");
       # Julia requires Pentium 4 (SSE2) or better
diff --git a/pkgs/development/compilers/mlton/default.nix b/pkgs/development/compilers/mlton/default.nix
index 583f6f80137f..6b6907b0b2e6 100644
--- a/pkgs/development/compilers/mlton/default.nix
+++ b/pkgs/development/compilers/mlton/default.nix
@@ -14,15 +14,15 @@ stdenv.mkDerivation rec {
   name = "mlton-${version}";
 
   binSrc =
-    if stdenv.system == "i686-linux" then (fetchurl {
+    if stdenv.hostPlatform.system == "i686-linux" then (fetchurl {
       url = "mirror://sourceforge/project/mlton/mlton/${version}/${name}-1.x86-linux.tgz";
       sha256 = "1kxjjmnw4xk2d9hpvz43w9dvyhb3025k4zvjx785c33nrwkrdn4j";
     })
-    else if stdenv.system == "x86_64-linux" then (fetchurl {
+    else if stdenv.hostPlatform.system == "x86_64-linux" then (fetchurl {
         url = "mirror://sourceforge/project/mlton/mlton/${version}/${name}-1.amd64-linux.tgz";
         sha256 = "0fyhwxb4nmpirjbjcvk9f6w67gmn2gkz7xcgz0xbfih9kc015ygn";
     })
-    else if stdenv.system == "x86_64-darwin" then (fetchurl {
+    else if stdenv.hostPlatform.system == "x86_64-darwin" then (fetchurl {
         url = "mirror://sourceforge/project/mlton/mlton/${version}/${name}-1.amd64-darwin.gmp-macports.tgz";
         sha256 = "044wnh9hhg6if886xy805683k0as347xd37r0r1yi4x7qlxzzgx9";
     })
diff --git a/pkgs/development/compilers/mozart/binary.nix b/pkgs/development/compilers/mozart/binary.nix
index ebe562fcde32..ef6cd1160b33 100644
--- a/pkgs/development/compilers/mozart/binary.nix
+++ b/pkgs/development/compilers/mozart/binary.nix
@@ -20,7 +20,7 @@ stdenv.mkDerivation {
 
   preferLocalBuild = true;
 
-  src = binaries."${stdenv.system}" or (throw "unsupported system: ${stdenv.system}");
+  src = binaries."${stdenv.hostPlatform.system}" or (throw "unsupported system: ${stdenv.hostPlatform.system}");
 
   libPath = stdenv.lib.makeLibraryPath
     [ stdenv.cc.cc
diff --git a/pkgs/development/compilers/nvidia-cg-toolkit/default.nix b/pkgs/development/compilers/nvidia-cg-toolkit/default.nix
index 21ccf77e4a24..b6e2aea7eca5 100644
--- a/pkgs/development/compilers/nvidia-cg-toolkit/default.nix
+++ b/pkgs/development/compilers/nvidia-cg-toolkit/default.nix
@@ -10,17 +10,17 @@ stdenv.mkDerivation rec {
   name = "nvidia-cg-toolkit-${version}";
 
   src =
-    if stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchurl {
         url = "https://developer.download.nvidia.com/cg/Cg_${version}/Cg-${version}_${date}_x86_64.tgz";
         sha256 = "e8ff01e6cc38d1b3fd56a083f5860737dbd2f319a39037528fb1a74a89ae9878";
       }
-    else if stdenv.system == "i686-linux" then
+    else if stdenv.hostPlatform.system == "i686-linux" then
       fetchurl {
         url = "http://developer.download.nvidia.com/cg/Cg_${version}/Cg-${version}_${date}_x86.tgz";
         sha256 = "cef3591e436f528852db0e8c145d3842f920e0c89bcfb219c466797cb7b18879";
       }
-    else throw "nvidia-cg-toolkit does not support platform ${stdenv.system}";
+    else throw "nvidia-cg-toolkit does not support platform ${stdenv.hostPlatform.system}";
 
   installPhase = ''
     for b in cgc cgfxcat cginfo
diff --git a/pkgs/development/compilers/opendylan/bin.nix b/pkgs/development/compilers/opendylan/bin.nix
index 1abf44f23495..9b721312bb78 100644
--- a/pkgs/development/compilers/opendylan/bin.nix
+++ b/pkgs/development/compilers/opendylan/bin.nix
@@ -5,15 +5,15 @@
 stdenv.mkDerivation {
   name = "opendylan-2013.2";
 
-  src = if stdenv.system == "x86_64-linux" then fetchurl {
+  src = if stdenv.hostPlatform.system == "x86_64-linux" then fetchurl {
       url = https://opendylan.org/downloads/opendylan/2013.2/opendylan-2013.2-x86_64-linux.tar.bz2;
       sha256 = "035brbw3hm7zrs593q4zc42yglj1gmmkw3b1r7zzlw3ks4i2lg7h";
     }
-    else if stdenv.system == "i686-linux" then fetchurl {
+    else if stdenv.hostPlatform.system == "i686-linux" then fetchurl {
       url = https://opendylan.org/downloads/opendylan/2013.2/opendylan-2013.2-x86-linux.tar.bz2;
       sha256 = "0c61ihvblcsjrw6ncr8x8ylhskcrqs8pajs4mg5di36cvqw12nq5";
     }
-    else throw "platform ${stdenv.system} not supported.";
+    else throw "platform ${stdenv.hostPlatform.system} not supported.";
 
   buildInputs = [ patchelf boehmgc gnused makeWrapper ];
 
diff --git a/pkgs/development/compilers/opendylan/default.nix b/pkgs/development/compilers/opendylan/default.nix
index 17d474359da4..8e732d7d8bf4 100644
--- a/pkgs/development/compilers/opendylan/default.nix
+++ b/pkgs/development/compilers/opendylan/default.nix
@@ -11,11 +11,11 @@ stdenv.mkDerivation {
     fetchSubmodules = true;
   };
 
-  buildInputs = (if stdenv.system == "i686-linux" then [ mps ] else [ boehmgc ]) ++ [
+  buildInputs = (if stdenv.hostPlatform.system == "i686-linux" then [ mps ] else [ boehmgc ]) ++ [
     opendylan-bootstrap boehmgc gnused autoconf automake perl makeWrapper
   ];
 
-  preConfigure = if stdenv.system == "i686-linux" then ''
+  preConfigure = if stdenv.hostPlatform.system == "i686-linux" then ''
     mkdir -p $TMPDIR/mps
     tar --strip-components=1 -xf ${mps.src} -C $TMPDIR/mps
     ./autogen.sh
@@ -25,7 +25,7 @@ stdenv.mkDerivation {
   '';
 
   configureFlags = [
-    (if stdenv.system == "i686-linux" then "--with-mps=$(TMPDIR)/mps" else "--with-gc=${boehmgc.out}")
+    (if stdenv.hostPlatform.system == "i686-linux" then "--with-mps=$(TMPDIR)/mps" else "--with-gc=${boehmgc.out}")
   ];
   buildPhase = "make 3-stage-bootstrap";
 
diff --git a/pkgs/development/compilers/openjdk/10.nix b/pkgs/development/compilers/openjdk/10.nix
index 6e8d9003bf43..750a4efe4968 100644
--- a/pkgs/development/compilers/openjdk/10.nix
+++ b/pkgs/development/compilers/openjdk/10.nix
@@ -13,7 +13,7 @@ let
    * The JRE libraries are in directories that depend on the CPU.
    */
   architecture =
-    if stdenv.system == "i686-linux" then
+    if stdenv.hostPlatform.system == "i686-linux" then
       "i386"
     else "amd64";
 
diff --git a/pkgs/development/compilers/oraclejdk/jdk-linux-base.nix b/pkgs/development/compilers/oraclejdk/jdk-linux-base.nix
index baa136b798d9..5d55e0554e55 100644
--- a/pkgs/development/compilers/oraclejdk/jdk-linux-base.nix
+++ b/pkgs/development/compilers/oraclejdk/jdk-linux-base.nix
@@ -46,7 +46,7 @@ let
     x86_64-linux  = "amd64";
     armv7l-linux  = "arm";
     aarch64-linux = "aarch64";
-  }.${stdenv.system};
+  }.${stdenv.hostPlatform.system};
 
   jce =
     if installjce then
@@ -77,9 +77,9 @@ let result = stdenv.mkDerivation rec {
       x86_64-linux  = "jdk-${productVersion}u${patchVersion}-linux-x64.tar.gz";
       armv7l-linux  = "jdk-${productVersion}u${patchVersion}-linux-arm32-vfp-hflt.tar.gz";
       aarch64-linux = "jdk-${productVersion}u${patchVersion}-linux-arm64-vfp-hflt.tar.gz";
-    }.${stdenv.system};
+    }.${stdenv.hostPlatform.system};
     url = downloadUrl;
-    sha256 = sha256.${stdenv.system};
+    sha256 = sha256.${stdenv.hostPlatform.system};
   };
 
   nativeBuildInputs = [ file ]
diff --git a/pkgs/development/compilers/orc/default.nix b/pkgs/development/compilers/orc/default.nix
index 9fc9007abb9e..3f3db48828d4 100644
--- a/pkgs/development/compilers/orc/default.nix
+++ b/pkgs/development/compilers/orc/default.nix
@@ -16,7 +16,7 @@ stdenv.mkDerivation rec {
   '';
 
   # https://bugzilla.gnome.org/show_bug.cgi?id=728129#c15
-  doCheck = stdenv.system != "i686-linux"; # not sure about cross-compiling
+  doCheck = stdenv.hostPlatform.system != "i686-linux"; # not sure about cross-compiling
 
   meta = with stdenv.lib; {
     description = "The Oil Runtime Compiler";
diff --git a/pkgs/development/compilers/picat/default.nix b/pkgs/development/compilers/picat/default.nix
index 8ee904a6ed6c..b520a5e703c8 100644
--- a/pkgs/development/compilers/picat/default.nix
+++ b/pkgs/development/compilers/picat/default.nix
@@ -8,8 +8,8 @@ stdenv.mkDerivation {
     sha256 = "0wvl95gf4pjs93632g4wi0mw1glzzhjp9g4xg93ll2zxggbxibli";
   };
 
-  ARCH = if stdenv.system == "i686-linux" then "linux32"
-         else if stdenv.system == "x86_64-linux" then "linux64"
+  ARCH = if stdenv.hostPlatform.system == "i686-linux" then "linux32"
+         else if stdenv.hostPlatform.system == "x86_64-linux" then "linux64"
          else throw "Unsupported system";
 
   hardeningDisable = [ "format" ];
diff --git a/pkgs/development/compilers/rust/bootstrap.nix b/pkgs/development/compilers/rust/bootstrap.nix
index 563250097ae1..901675ff31b4 100644
--- a/pkgs/development/compilers/rust/bootstrap.nix
+++ b/pkgs/development/compilers/rust/bootstrap.nix
@@ -16,19 +16,19 @@ let
   };
 
   platform =
-    if stdenv.system == "i686-linux"
+    if stdenv.hostPlatform.system == "i686-linux"
     then "i686-unknown-linux-gnu"
-    else if stdenv.system == "x86_64-linux"
+    else if stdenv.hostPlatform.system == "x86_64-linux"
     then "x86_64-unknown-linux-gnu"
-    else if stdenv.system == "armv7l-linux"
+    else if stdenv.hostPlatform.system == "armv7l-linux"
     then "armv7-unknown-linux-gnueabihf"
-    else if stdenv.system == "aarch64-linux"
+    else if stdenv.hostPlatform.system == "aarch64-linux"
     then "aarch64-unknown-linux-gnu"
-    else if stdenv.system == "i686-darwin"
+    else if stdenv.hostPlatform.system == "i686-darwin"
     then "i686-apple-darwin"
-    else if stdenv.system == "x86_64-darwin"
+    else if stdenv.hostPlatform.system == "x86_64-darwin"
     then "x86_64-apple-darwin"
-    else throw "missing bootstrap url for platform ${stdenv.system}";
+    else throw "missing bootstrap url for platform ${stdenv.hostPlatform.system}";
 
   src = fetchurl {
      url = "https://static.rust-lang.org/dist/rust-${version}-${platform}.tar.gz";
diff --git a/pkgs/development/compilers/sbcl/bootstrap.nix b/pkgs/development/compilers/sbcl/bootstrap.nix
index 529123398a57..ee662d39e451 100644
--- a/pkgs/development/compilers/sbcl/bootstrap.nix
+++ b/pkgs/development/compilers/sbcl/bootstrap.nix
@@ -39,9 +39,9 @@ let
       sha256 = "05c12fmac4ha72k1ckl6i780rckd7jh4g5s5hiic7fjxnf1kx8d0";
     };
   };
-  cfg = options.${stdenv.system};
+  cfg = options.${stdenv.hostPlatform.system};
 in
-assert builtins.hasAttr stdenv.system options;
+assert builtins.hasAttr stdenv.hostPlatform.system options;
 stdenv.mkDerivation rec {
   name    = "sbcl-bootstrap-${version}";
   version = cfg.version;
diff --git a/pkgs/development/compilers/sbcl/default.nix b/pkgs/development/compilers/sbcl/default.nix
index 261a2fb6432c..a860aa7dc734 100644
--- a/pkgs/development/compilers/sbcl/default.nix
+++ b/pkgs/development/compilers/sbcl/default.nix
@@ -1,6 +1,6 @@
 { stdenv, fetchurl, writeText, sbclBootstrap
 , sbclBootstrapHost ? "${sbclBootstrap}/bin/sbcl --disable-debugger --no-userinit --no-sysinit"
-, threadSupport ? (stdenv.isi686 || stdenv.isx86_64 || "aarch64-linux" == stdenv.system)
+, threadSupport ? (stdenv.isi686 || stdenv.isx86_64 || "aarch64-linux" == stdenv.hostPlatform.system)
   # Meant for sbcl used for creating binaries portable to non-NixOS via save-lisp-and-die.
   # Note that the created binaries still need `patchelf --set-interpreter ...`
   # to get rid of ${glibc} dependency.
diff --git a/pkgs/development/interpreters/dart/default.nix b/pkgs/development/interpreters/dart/default.nix
index ae7f8686b781..4c697ec4e802 100644
--- a/pkgs/development/interpreters/dart/default.nix
+++ b/pkgs/development/interpreters/dart/default.nix
@@ -45,7 +45,7 @@ stdenv.mkDerivation {
     unzip
   ];
 
-  src = sources."${version}-${stdenv.system}" or (throw "unsupported version/system: ${version}/${stdenv.system}");
+  src = sources."${version}-${stdenv.hostPlatform.system}" or (throw "unsupported version/system: ${version}/${stdenv.hostPlatform.system}");
 
   installPhase = ''
     mkdir -p $out
diff --git a/pkgs/development/interpreters/spidermonkey/1.8.5.nix b/pkgs/development/interpreters/spidermonkey/1.8.5.nix
index bd53450de4ef..466371955868 100644
--- a/pkgs/development/interpreters/spidermonkey/1.8.5.nix
+++ b/pkgs/development/interpreters/spidermonkey/1.8.5.nix
@@ -43,7 +43,7 @@ stdenv.mkDerivation rec {
   # of polkit, which is what matters most, it does not override the allocator
   # so the failure of that test does not matter much.
   configureFlags = [ "--enable-threadsafe" "--with-system-nspr" ] ++
-    stdenv.lib.optionals (stdenv.system == "armv5tel-linux") [
+    stdenv.lib.optionals (stdenv.hostPlatform.system == "armv5tel-linux") [
         "--with-cpu-arch=armv5t" 
         "--disable-tracejit" ];
 
diff --git a/pkgs/development/libraries/apr/default.nix b/pkgs/development/libraries/apr/default.nix
index 7d7acf90a95c..705f61445b59 100644
--- a/pkgs/development/libraries/apr/default.nix
+++ b/pkgs/development/libraries/apr/default.nix
@@ -26,7 +26,7 @@ stdenv.mkDerivation rec {
   configureFlags =
     # Including the Windows headers breaks unistd.h.
     # Based on ftp://sourceware.org/pub/cygwin/release/libapr1/libapr1-1.3.8-2-src.tar.bz2
-    stdenv.lib.optional (stdenv.system == "i686-cygwin") "ac_cv_header_windows_h=no";
+    stdenv.lib.optional (stdenv.hostPlatform.system == "i686-cygwin") "ac_cv_header_windows_h=no";
 
   enableParallelBuilding = true;
 
diff --git a/pkgs/development/libraries/audio/libbass/default.nix b/pkgs/development/libraries/audio/libbass/default.nix
index ec93e2f64671..390ca6bb04b7 100644
--- a/pkgs/development/libraries/audio/libbass/default.nix
+++ b/pkgs/development/libraries/audio/libbass/default.nix
@@ -41,8 +41,8 @@ let
     dontBuild = true;
     installPhase =
       let so =
-            if bass.so ? ${stdenv.system} then bass.so.${stdenv.system}
-            else throw "${name} not packaged for ${stdenv.system} (yet).";
+            if bass.so ? ${stdenv.hostPlatform.system} then bass.so.${stdenv.hostPlatform.system}
+            else throw "${name} not packaged for ${stdenv.hostPlatform.system} (yet).";
       in ''
         mkdir -p $out/{lib,include}
         install -m644 -t $out/lib/ ${so}
diff --git a/pkgs/development/libraries/bootil/default.nix b/pkgs/development/libraries/bootil/default.nix
index 160f62305945..b64cdd5245fd 100644
--- a/pkgs/development/libraries/bootil/default.nix
+++ b/pkgs/development/libraries/bootil/default.nix
@@ -28,7 +28,7 @@ stdenv.mkDerivation rec {
   platform =
     if stdenv.isLinux then "linux"
     else if stdenv.isDarwin then "macosx"
-    else throw "unrecognized system ${stdenv.system}";
+    else throw "unrecognized system ${stdenv.hostPlatform.system}";
 
   buildInputs = [ premake4 ];
 
diff --git a/pkgs/development/libraries/crypto++/default.nix b/pkgs/development/libraries/crypto++/default.nix
index ba5b2aa43718..cbd3e4054159 100644
--- a/pkgs/development/libraries/crypto++/default.nix
+++ b/pkgs/development/libraries/crypto++/default.nix
@@ -12,9 +12,10 @@ stdenv.mkDerivation rec {
     sha256 = "1yk7jyf4va9425cg05llskpls2jm7n3jwy2hj5jm74zkr4mwpvl7";
   };
 
-  patches = with stdenv;
-    lib.optional (system != "i686-cygwin") ./dll.patch
-    ++ lib.optional isDarwin ./GNUmakefile-darwin.patch;
+  patches = stdenv.lib.concatLists [
+    (stdenv.lib.optional (stdenv.hostPlatform.system != "i686-cygwin") ./dll.patch)
+    (stdenv.lib.optional stdenv.hostPlatform.isDarwin ./GNUmakefile-darwin.patch)
+  ];
 
 
   configurePhase = let
diff --git a/pkgs/development/libraries/gpgme/default.nix b/pkgs/development/libraries/gpgme/default.nix
index b3b00a1c7226..71fe23ea6b0d 100644
--- a/pkgs/development/libraries/gpgme/default.nix
+++ b/pkgs/development/libraries/gpgme/default.nix
@@ -7,7 +7,10 @@
 , withPython ? false, swig2 ? null, python ? null
 }:
 
-let inherit (stdenv) lib system; in
+let
+  inherit (stdenv) lib;
+  inherit (stdenv.hostPlatform) system;
+in
 
 stdenv.mkDerivation rec {
   name = "gpgme-${version}";
diff --git a/pkgs/development/libraries/gsl/default.nix b/pkgs/development/libraries/gsl/default.nix
index 37d4843db8d4..8a419d678655 100644
--- a/pkgs/development/libraries/gsl/default.nix
+++ b/pkgs/development/libraries/gsl/default.nix
@@ -14,7 +14,7 @@ stdenv.mkDerivation rec {
   ];
 
   # https://lists.gnu.org/archive/html/bug-gsl/2015-11/msg00012.html
-  doCheck = stdenv.system != "i686-linux" && stdenv.system != "aarch64-linux";
+  doCheck = stdenv.hostPlatform.system != "i686-linux" && stdenv.hostPlatform.system != "aarch64-linux";
 
   meta = {
     description = "The GNU Scientific Library, a large numerical library";
diff --git a/pkgs/development/libraries/java/jzmq/default.nix b/pkgs/development/libraries/java/jzmq/default.nix
index 7d229d2577ab..402f893034b6 100644
--- a/pkgs/development/libraries/java/jzmq/default.nix
+++ b/pkgs/development/libraries/java/jzmq/default.nix
@@ -15,7 +15,7 @@ stdenv.mkDerivation rec {
   buildInputs = [ zeromq3 jdk ];
 
   preConfigure = ''
-    ${if stdenv.system == "x86_64-darwin" then
+    ${if stdenv.hostPlatform.system == "x86_64-darwin" then
       '' sed -i -e 's~/Headers~/include~' -e 's~_JNI_INC_SUBDIRS=\".*\"~_JNI_INC_SUBDIRS=\"darwin\"~' configure
       '' else ""}
   '';
diff --git a/pkgs/development/libraries/java/swt/default.nix b/pkgs/development/libraries/java/swt/default.nix
index 1a7153f99e67..0aa20f8b014f 100644
--- a/pkgs/development/libraries/java/swt/default.nix
+++ b/pkgs/development/libraries/java/swt/default.nix
@@ -16,7 +16,7 @@ let
         sha256 = "00k1mfbncvyh8klgmk0891w8jwnd5niqb16j1j8yacrm2smmlb05"; };
   };
 
-  metadata = assert platformMap ? ${stdenv.system}; platformMap.${stdenv.system};
+  metadata = assert platformMap ? ${stdenv.hostPlatform.system}; platformMap.${stdenv.hostPlatform.system};
 
 in stdenv.mkDerivation rec {
   version = "4.5";
diff --git a/pkgs/development/libraries/libspotify/default.nix b/pkgs/development/libraries/libspotify/default.nix
index 3a01ff2944db..e472fe014ee7 100644
--- a/pkgs/development/libraries/libspotify/default.nix
+++ b/pkgs/development/libraries/libspotify/default.nix
@@ -2,26 +2,26 @@
 
 let
   version = "12.1.51";
-  isLinux = (stdenv.system == "x86_64-linux" || stdenv.system == "i686-linux");
+  isLinux = (stdenv.hostPlatform.system == "x86_64-linux" || stdenv.hostPlatform.system == "i686-linux");
 in
 
-if (stdenv.system != "x86_64-linux" && stdenv.system != "x86_64-darwin" && stdenv.system != "i686-linux")
+if (stdenv.hostPlatform.system != "x86_64-linux" && stdenv.hostPlatform.system != "x86_64-darwin" && stdenv.hostPlatform.system != "i686-linux")
 then throw "Check https://developer.spotify.com/technologies/libspotify/ for a tarball for your system and add it here"
 else stdenv.mkDerivation {
   name = "libspotify-${version}";
 
   src =
-    if stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchurl {
         url    = "https://developer.spotify.com/download/libspotify/libspotify-${version}-Linux-x86_64-release.tar.gz";
         sha256 = "0n0h94i4xg46hfba95n3ypah93crwb80bhgsg00f6sms683lx8a3";
       }
-    else if stdenv.system == "x86_64-darwin" then
+    else if stdenv.hostPlatform.system == "x86_64-darwin" then
       fetchurl {
         url    = "https://developer.spotify.com/download/libspotify/libspotify-${version}-Darwin-universal.zip";
         sha256 = "1gcgrc8arim3hnszcc886lmcdb4iigc08abkaa02l6gng43ky1c0";
       }
-    else if stdenv.system == "i686-linux" then
+    else if stdenv.hostPlatform.system == "i686-linux" then
       fetchurl {
         url    = "https://developer.spotify.com/download/libspotify/libspotify-${version}-Linux-i686-release.tar.gz";
         sha256 = "1bjmn64gbr4p9irq426yap4ipq9rb84zsyhjjr7frmmw22xb86ll";
@@ -46,7 +46,7 @@ else stdenv.mkDerivation {
 
 
   # darwin-specific
-  buildInputs = stdenv.lib.optional (stdenv.system == "x86_64-darwin") unzip;
+  buildInputs = stdenv.lib.optional (stdenv.hostPlatform.system == "x86_64-darwin") unzip;
 
   # linux-specific
   installFlags = stdenv.lib.optionalString (isLinux)
diff --git a/pkgs/development/libraries/live555/default.nix b/pkgs/development/libraries/live555/default.nix
index e0cf3328bac2..4dd5d8bcd26f 100644
--- a/pkgs/development/libraries/live555/default.nix
+++ b/pkgs/development/libraries/live555/default.nix
@@ -28,7 +28,7 @@ stdenv.mkDerivation {
       i686-linux = "linux";
       x86_64-linux = "linux-64bit";
       aarch64-linux = "linux-64bit";
-    }.${stdenv.system}}
+    }.${stdenv.hostPlatform.system}}
   '';
 
   installPhase = ''
diff --git a/pkgs/development/libraries/mesa/default.nix b/pkgs/development/libraries/mesa/default.nix
index e1a9477dcd63..063ed381e01a 100644
--- a/pkgs/development/libraries/mesa/default.nix
+++ b/pkgs/development/libraries/mesa/default.nix
@@ -23,7 +23,7 @@
 
 with stdenv.lib;
 
-if ! lists.elem stdenv.system platforms.mesaPlatforms then
+if ! lists.elem stdenv.hostPlatform.system platforms.mesaPlatforms then
   throw "unsupported platform for Mesa"
 else
 
diff --git a/pkgs/development/libraries/nettle/generic.nix b/pkgs/development/libraries/nettle/generic.nix
index 3af93469cf16..2ef367b6c53a 100644
--- a/pkgs/development/libraries/nettle/generic.nix
+++ b/pkgs/development/libraries/nettle/generic.nix
@@ -16,11 +16,11 @@ stdenv.mkDerivation (rec {
   nativeBuildInputs = [ gnum4 ];
   propagatedBuildInputs = [ gmp ];
 
-  doCheck = (stdenv.system != "i686-cygwin" && !stdenv.isDarwin);
+  doCheck = (stdenv.hostPlatform.system != "i686-cygwin" && !stdenv.isDarwin);
 
   enableParallelBuilding = true;
 
-  patches = stdenv.lib.optional (stdenv.system == "i686-cygwin")
+  patches = stdenv.lib.optional (stdenv.hostPlatform.system == "i686-cygwin")
               ./cygwin.patch;
 
   meta = with stdenv.lib; {
diff --git a/pkgs/development/libraries/opencv/3.x.nix b/pkgs/development/libraries/opencv/3.x.nix
index e97aa0d391e0..81d106a2a40c 100644
--- a/pkgs/development/libraries/opencv/3.x.nix
+++ b/pkgs/development/libraries/opencv/3.x.nix
@@ -63,11 +63,11 @@ let
       sha256 = "1ys9mshfpm8iy8h4ml792gnqrq959dsrcv26axx14niivxyjbji8";
     } + "/ippicv";
     files = let name = platform : "ippicv_2017u3_${platform}_general_20180518.tgz"; in
-      if stdenv.system == "x86_64-linux" then
+      if stdenv.hostPlatform.system == "x86_64-linux" then
       { ${name "lnx_intel64"} = "b7cc351267db2d34b9efa1cd22ff0572"; }
-      else if stdenv.system == "i686-linux" then
+      else if stdenv.hostPlatform.system == "i686-linux" then
       { ${name "lnx_ia32"}    = "ea72de74dae3c604eb6348395366e78e"; }
-      else if stdenv.system == "x86_64-darwin" then
+      else if stdenv.hostPlatform.system == "x86_64-darwin" then
       { ${name "mac_intel64"} = "3ae52b9be0fe73dd45bc5e9429cd3732"; }
       else
       throw "ICV is not available for this platform (or not yet supported by this package)";
diff --git a/pkgs/development/libraries/oracle-instantclient/default.nix b/pkgs/development/libraries/oracle-instantclient/default.nix
index 0c05e2ec5f61..fe260e0c2ad2 100644
--- a/pkgs/development/libraries/oracle-instantclient/default.nix
+++ b/pkgs/development/libraries/oracle-instantclient/default.nix
@@ -14,12 +14,12 @@ let
     sha256 = hash;
   });
 
-  throwSystem = throw "Unsupported system: ${stdenv.system}";
+  throwSystem = throw "Unsupported system: ${stdenv.hostPlatform.system}";
 
   arch = {
     "x86_64-linux" = "linux.x64";
     "x86_64-darwin" = "macos.x64";
-  }."${stdenv.system}" or throwSystem;
+  }."${stdenv.hostPlatform.system}" or throwSystem;
 
   srcs = {
     "x86_64-linux" = [
@@ -32,7 +32,7 @@ let
       (requireSource "sdk" arch version "2" "e0befca9c4e71ebc9f444957ffa70f01aeeec5976ea27c40406471b04c34848b")
       (requireSource "sqlplus" arch version "2" "d147cbb5b2a954fdcb4b642df4f0bd1153fd56e0f56e7fa301601b4f7e2abe0e") ]
       ++ optional odbcSupport (requireSource "odbc" arch version "2" "1805c1ab6c8c5e8df7bdcc35d7f2b94c329ecf4dff9bde55d5f9b159ecd8b64e");
-  }."${stdenv.system}" or throwSystem;
+  }."${stdenv.hostPlatform.system}" or throwSystem;
 
   extLib = stdenv.hostPlatform.extensions.sharedLibrary;
 in stdenv.mkDerivation rec {
diff --git a/pkgs/development/libraries/physics/geant4/fetch.nix b/pkgs/development/libraries/physics/geant4/fetch.nix
index 7dc4c8656279..5d539b480d7d 100644
--- a/pkgs/development/libraries/physics/geant4/fetch.nix
+++ b/pkgs/development/libraries/physics/geant4/fetch.nix
@@ -1,7 +1,7 @@
 { stdenv, fetchurl }:
 
 let
-  fetch = { version, src ? builtins.getAttr stdenv.system sources, sources ? null }:
+  fetch = { version, src ? builtins.getAttr stdenv.hostPlatform.system sources, sources ? null }:
   {
     inherit version src;
   };
diff --git a/pkgs/development/libraries/science/math/openblas/default.nix b/pkgs/development/libraries/science/math/openblas/default.nix
index 18483f9e327c..b5efdc585848 100644
--- a/pkgs/development/libraries/science/math/openblas/default.nix
+++ b/pkgs/development/libraries/science/math/openblas/default.nix
@@ -67,15 +67,15 @@ in
 
 let
   config =
-    configs.${stdenv.system}
-    or (throw "unsupported system: ${stdenv.system}");
+    configs.${stdenv.hostPlatform.system}
+    or (throw "unsupported system: ${stdenv.hostPlatform.system}");
 in
 
 let
   blas64 =
     if blas64_ != null
       then blas64_
-      else hasPrefix "x86_64" stdenv.system;
+      else hasPrefix "x86_64" stdenv.hostPlatform.system;
 in
 stdenv.mkDerivation rec {
   name = "openblas-${version}";
diff --git a/pkgs/development/libraries/scmccid/default.nix b/pkgs/development/libraries/scmccid/default.nix
index f88bd64f597b..b305fecc3933 100644
--- a/pkgs/development/libraries/scmccid/default.nix
+++ b/pkgs/development/libraries/scmccid/default.nix
@@ -5,11 +5,11 @@ assert stdenv ? cc && stdenv.cc.libc != null;
 stdenv.mkDerivation rec {
   name = "scmccid-5.0.11";
 
-  src = if stdenv.system == "i686-linux" then (fetchurl {
+  src = if stdenv.hostPlatform.system == "i686-linux" then (fetchurl {
       url = "http://www.scmmicro.com/support/download/scmccid_5.0.11_linux.tar.gz";
       sha256 = "1r5wkarhzl09ncgj55baizf573czw0nplh1pgddzx9xck66kh5bm";
     })
-    else if stdenv.system == "x86_64-linux" then (fetchurl {
+    else if stdenv.hostPlatform.system == "x86_64-linux" then (fetchurl {
         url = "http://www.scmmicro.com/support/download/scmccid_5.0.11_linux_x64.tar.gz";
         sha256 = "0k9lzlk01sl4ycfqgrqqy3bildz0mcr1r0kkicgjz96l4s0jgz0i";
     })
diff --git a/pkgs/development/libraries/skalibs/default.nix b/pkgs/development/libraries/skalibs/default.nix
index b3f5e12b0ecd..9d5bd170e20d 100644
--- a/pkgs/development/libraries/skalibs/default.nix
+++ b/pkgs/development/libraries/skalibs/default.nix
@@ -33,7 +33,7 @@ in stdenv.mkDerivation rec {
   # Explicitly setting target ensures code can be compiled against a skalibs
   # binary built on a different version of darwin.
   # http://www.skarnet.org/cgi-bin/archive.cgi?1:mss:623:heiodchokfjdkonfhdph
-  ++ (stdenv.lib.optional stdenv.isDarwin "--build=${stdenv.system}");
+  ++ (stdenv.lib.optional stdenv.isDarwin "--build=${stdenv.hostPlatform.system}");
 
   postInstall = ''
     mkdir -p $doc/share/doc/skalibs
diff --git a/pkgs/development/libraries/tachyon/default.nix b/pkgs/development/libraries/tachyon/default.nix
index d5d12e44df0a..27ac0fdd5ff9 100644
--- a/pkgs/development/libraries/tachyon/default.nix
+++ b/pkgs/development/libraries/tachyon/default.nix
@@ -34,15 +34,15 @@ stdenv.mkDerivation rec {
     export USEPNG=" -DUSEPNG"
     export PNGLIB=" -lpng -lz"
   '';
-  arch = if stdenv.system == "x86_64-linux"   then "linux-64-thr"  else
-         if stdenv.system == "i686-linux"     then "linux-thr"     else
-         if stdenv.system == "aarch64-linux"  then "linux-arm-thr" else
-         if stdenv.system == "armv7l-linux"   then "linux-arm-thr" else
-         if stdenv.system == "x86_64-darwin"  then "macosx-thr"    else
-         if stdenv.system == "i686-darwin"    then "macosx-64-thr" else
-         if stdenv.system == "i686-cygwin"    then "win32"         else
-         if stdenv.system == "x86_64-freebsd" then "bsd"           else
-         if stdenv.system == "x686-freebsd"   then "bsd"           else
+  arch = if stdenv.hostPlatform.system == "x86_64-linux"   then "linux-64-thr"  else
+         if stdenv.hostPlatform.system == "i686-linux"     then "linux-thr"     else
+         if stdenv.hostPlatform.system == "aarch64-linux"  then "linux-arm-thr" else
+         if stdenv.hostPlatform.system == "armv7l-linux"   then "linux-arm-thr" else
+         if stdenv.hostPlatform.system == "x86_64-darwin"  then "macosx-thr"    else
+         if stdenv.hostPlatform.system == "i686-darwin"    then "macosx-64-thr" else
+         if stdenv.hostPlatform.system == "i686-cygwin"    then "win32"         else
+         if stdenv.hostPlatform.system == "x86_64-freebsd" then "bsd"           else
+         if stdenv.hostPlatform.system == "x686-freebsd"   then "bsd"           else
          throw "Don't know what arch to select for tachyon build";
   makeFlags = "${arch}";
   patches = [
diff --git a/pkgs/development/libraries/v8/3.14.nix b/pkgs/development/libraries/v8/3.14.nix
index ce666becc855..827274251ed9 100644
--- a/pkgs/development/libraries/v8/3.14.nix
+++ b/pkgs/development/libraries/v8/3.14.nix
@@ -65,7 +65,7 @@ stdenv.mkDerivation rec {
 
   installPhase = ''
     install -vD out/Release/d8 "$out/bin/d8"
-    ${if stdenv.system == "x86_64-darwin" then ''
+    ${if stdenv.hostPlatform.system == "x86_64-darwin" then ''
     install -vD out/Release/lib.target/libv8.dylib "$out/lib/libv8.dylib"
     '' else ''
     install -vD out/Release/lib.target/libv8.so "$out/lib/libv8.so"
diff --git a/pkgs/development/libraries/vigra/default.nix b/pkgs/development/libraries/vigra/default.nix
index 4a002becdb3b..12c166beacbd 100644
--- a/pkgs/development/libraries/vigra/default.nix
+++ b/pkgs/development/libraries/vigra/default.nix
@@ -21,7 +21,7 @@ in stdenv.mkDerivation rec {
   preConfigure = "cmakeFlags+=\" -DVIGRANUMPY_INSTALL_DIR=$out/lib/${python.libPrefix}/site-packages\"";
 
   cmakeFlags = [ "-DWITH_OPENEXR=1" ]
-            ++ stdenv.lib.optionals (stdenv.system == "x86_64-linux")
+            ++ stdenv.lib.optionals (stdenv.hostPlatform.system == "x86_64-linux")
                   [ "-DCMAKE_CXX_FLAGS=-fPIC" "-DCMAKE_C_FLAGS=-fPIC" ];
 
   enableParallelBuilding = true;
diff --git a/pkgs/development/libraries/vxl/default.nix b/pkgs/development/libraries/vxl/default.nix
index b9f3c0e64d6c..777b8bb1f403 100644
--- a/pkgs/development/libraries/vxl/default.nix
+++ b/pkgs/development/libraries/vxl/default.nix
@@ -15,7 +15,7 @@ stdenv.mkDerivation {
   # in stdenv linux headers
   # BUILD_BRL fails to find open()
   cmakeFlags = "-DBUILD_TESTING=OFF -DBUILD_OUL=OFF -DBUILD_BRL=OFF -DBUILD_CONTRIB=OFF "
-    + (if stdenv.system == "x86_64-linux" then
+    + (if stdenv.hostPlatform.system == "x86_64-linux" then
       "-DCMAKE_CXX_FLAGS=-fPIC -DCMAKE_C_FLAGS=-fPIC"
     else
       "");
diff --git a/pkgs/development/libraries/wtk/default.nix b/pkgs/development/libraries/wtk/default.nix
index 0ed4f24ef86b..2791c97f5ae6 100644
--- a/pkgs/development/libraries/wtk/default.nix
+++ b/pkgs/development/libraries/wtk/default.nix
@@ -1,6 +1,6 @@
 { stdenv, requireFile, unzip, xorg }:
 
-assert stdenv.system == "i686-linux";
+assert stdenv.hostPlatform.system == "i686-linux";
 
 stdenv.mkDerivation rec {
   name = "sun-java-wtk-2.5.2_01";
diff --git a/pkgs/development/misc/amdapp-sdk/default.nix b/pkgs/development/misc/amdapp-sdk/default.nix
index 7da0fc148d42..79651db23ea4 100644
--- a/pkgs/development/misc/amdapp-sdk/default.nix
+++ b/pkgs/development/misc/amdapp-sdk/default.nix
@@ -5,10 +5,10 @@
 
 let
 
-  bits = if stdenv.system == "x86_64-linux" then "64"
+  bits = if stdenv.hostPlatform.system == "x86_64-linux" then "64"
          else "32";
 
-  arch = if stdenv.system == "x86_64-linux" then "x86_64"
+  arch = if stdenv.hostPlatform.system == "x86_64-linux" then "x86_64"
          else "x86";
 
   src_info = {
diff --git a/pkgs/development/mobile/androidenv/androidndk.nix b/pkgs/development/mobile/androidenv/androidndk.nix
index 972c8a5dfbce..3ccdb237f894 100644
--- a/pkgs/development/mobile/androidenv/androidndk.nix
+++ b/pkgs/development/mobile/androidenv/androidndk.nix
@@ -10,10 +10,10 @@ stdenv.mkDerivation rec {
   name = "android-ndk-r${version}";
   inherit version;
 
-  src = if stdenv.system == "x86_64-linux" then fetchurl {
+  src = if stdenv.hostPlatform.system == "x86_64-linux" then fetchurl {
       url = "https://dl.google.com/android/repository/${name}-linux-x86_64.zip";
       inherit sha256;
-    } else throw "platform ${stdenv.system} not supported!";
+    } else throw "platform ${stdenv.hostPlatform.system} not supported!";
 
   phases = "buildPhase";
 
diff --git a/pkgs/development/mobile/androidenv/androidndk_r8e.nix b/pkgs/development/mobile/androidenv/androidndk_r8e.nix
index 3c12e16277d9..68d2150f972e 100644
--- a/pkgs/development/mobile/androidenv/androidndk_r8e.nix
+++ b/pkgs/development/mobile/androidenv/androidndk_r8e.nix
@@ -9,16 +9,16 @@
 stdenv.mkDerivation rec {
   name = "android-ndk-r8e";
 
-  src = if stdenv.system == "i686-linux"
+  src = if stdenv.hostPlatform.system == "i686-linux"
     then fetchurl {
       url = "http://dl.google.com/android/ndk/${name}-linux-x86.tar.bz2";
       sha256 = "c2c4e0c8b3037149a0f5dbb08d72f814a52af4da9fff9d80328c675457e95a98";
     }
-    else if stdenv.system == "x86_64-linux" then fetchurl {
+    else if stdenv.hostPlatform.system == "x86_64-linux" then fetchurl {
       url = "http://dl.google.com/android/ndk/${name}-linux-x86_64.tar.bz2";
       sha256 = "093gf55zbh38p2gk5bdykj1vg9p5l774wjdzw5mhk4144jm1wdq7";
     }
-    else throw "platform ${stdenv.system} not supported!";
+    else throw "platform ${stdenv.hostPlatform.system} not supported!";
 
   phases = "buildPhase";
 
diff --git a/pkgs/development/mobile/androidenv/androidsdk.nix b/pkgs/development/mobile/androidenv/androidsdk.nix
index 503e4f5c889b..5f61f25d54ee 100644
--- a/pkgs/development/mobile/androidenv/androidsdk.nix
+++ b/pkgs/development/mobile/androidenv/androidsdk.nix
@@ -22,16 +22,16 @@ stdenv.mkDerivation rec {
   name = "android-sdk-${version}";
   version = "25.2.5";
 
-  src = if (stdenv.system == "i686-linux" || stdenv.system == "x86_64-linux")
+  src = if (stdenv.hostPlatform.system == "i686-linux" || stdenv.hostPlatform.system == "x86_64-linux")
     then fetchurl {
       url = "https://dl.google.com/android/repository/tools_r${version}-linux.zip";
       sha256 = "0gnk49pkwy4m0nqwm1xnf3w4mfpi9w0kk7841xlawpwbkj0icxap";
     }
-    else if stdenv.system == "x86_64-darwin" then fetchurl {
+    else if stdenv.hostPlatform.system == "x86_64-darwin" then fetchurl {
       url = "http://dl.google.com/android/repository/tools_r${version}-macosx.zip";
       sha256 = "0yg7wjmyw70xsh8k4hgbqb5rilam2a94yc8dwbh7fjwqcmpxgwqb";
     }
-    else throw "platform not ${stdenv.system} supported!";
+    else throw "platform not ${stdenv.hostPlatform.system} supported!";
 
   buildCommand = ''
     mkdir -p $out/libexec
@@ -44,7 +44,7 @@ stdenv.mkDerivation rec {
         sed -i -e "s|/bin/ls|${coreutils}/bin/ls|" "$f"
     done
 
-    ${stdenv.lib.optionalString (stdenv.system == "i686-linux" || stdenv.system == "x86_64-linux")
+    ${stdenv.lib.optionalString (stdenv.hostPlatform.system == "i686-linux" || stdenv.hostPlatform.system == "x86_64-linux")
     ''
       # There are a number of native binaries. We must patch them to let them find the interpreter and libstdc++
 
@@ -54,7 +54,7 @@ stdenv.mkDerivation rec {
           patchelf --set-rpath ${stdenv_32bit.cc.cc.lib}/lib $i
       done
 
-      ${stdenv.lib.optionalString (stdenv.system == "x86_64-linux") ''
+      ${stdenv.lib.optionalString (stdenv.hostPlatform.system == "x86_64-linux") ''
         for i in bin64/{mkfs.ext4,fsck.ext4,e2fsck,tune2fs,resize2fs}
         do
             patchelf --set-interpreter ${stdenv.cc.libc.out}/lib/ld-linux-x86-64.so.2 $i
@@ -62,7 +62,7 @@ stdenv.mkDerivation rec {
         done
       ''}
 
-      ${stdenv.lib.optionalString (stdenv.system == "x86_64-linux") ''
+      ${stdenv.lib.optionalString (stdenv.hostPlatform.system == "x86_64-linux") ''
         # We must also patch the 64-bit emulator instances, if needed
 
         for i in emulator emulator64-arm emulator64-mips emulator64-x86 emulator64-crash-service emulator-check qemu/linux-x86_64/qemu-system-*
@@ -89,7 +89,7 @@ stdenv.mkDerivation rec {
 
       # The emulators need additional libraries, which are dynamically loaded => let's wrap them
 
-      ${stdenv.lib.optionalString (stdenv.system == "x86_64-linux") ''
+      ${stdenv.lib.optionalString (stdenv.hostPlatform.system == "x86_64-linux") ''
         for i in emulator emulator64-arm emulator64-mips emulator64-x86 emulator64-crash-service
         do
             wrapProgram `pwd`/$i \
@@ -102,7 +102,7 @@ stdenv.mkDerivation rec {
 
     patchShebangs .
 
-    ${if stdenv.system == "i686-linux" then
+    ${if stdenv.hostPlatform.system == "i686-linux" then
       ''
         # The monitor requires some more patching
 
@@ -115,7 +115,7 @@ stdenv.mkDerivation rec {
 
         cd ../..
       ''
-      else if stdenv.system == "x86_64-linux" then
+      else if stdenv.hostPlatform.system == "x86_64-linux" then
       ''
         # The monitor requires some more patching
 
diff --git a/pkgs/development/mobile/androidenv/build-tools.nix b/pkgs/development/mobile/androidenv/build-tools.nix
index 457a9b6720af..85e604bd3f44 100644
--- a/pkgs/development/mobile/androidenv/build-tools.nix
+++ b/pkgs/development/mobile/androidenv/build-tools.nix
@@ -3,16 +3,16 @@
 stdenv.mkDerivation rec {
   version = "26.0.2";
   name = "android-build-tools-r${version}";
-  src = if (stdenv.system == "i686-linux" || stdenv.system == "x86_64-linux")
+  src = if (stdenv.hostPlatform.system == "i686-linux" || stdenv.hostPlatform.system == "x86_64-linux")
     then fetchurl {
       url = "https://dl.google.com/android/repository/build-tools_r${version}-linux.zip";
       sha256 = "1kii880bwhjkc343zwx1ysxyisxhczrwhphnxbwsgi45mjgq8lm7";
     }
-    else if stdenv.system == "x86_64-darwin" then fetchurl {
+    else if stdenv.hostPlatform.system == "x86_64-darwin" then fetchurl {
       url = "https://dl.google.com/android/repository/build-tools_r${version}-macosx.zip";
       sha256 = "1x0ycprl6hgsm23kck5ind7x00hzydc5k3h3ch4a13407xbpvzvx";
     }
-    else throw "System ${stdenv.system} not supported!";
+    else throw "System ${stdenv.hostPlatform.system} not supported!";
 
   buildCommand = ''
     mkdir -p $out/build-tools
@@ -20,7 +20,7 @@ stdenv.mkDerivation rec {
     unzip $src
     mv android-* ${version}
 
-    ${stdenv.lib.optionalString (stdenv.system == "i686-linux" || stdenv.system == "x86_64-linux")
+    ${stdenv.lib.optionalString (stdenv.hostPlatform.system == "i686-linux" || stdenv.hostPlatform.system == "x86_64-linux")
       ''
         cd ${version}
 
diff --git a/pkgs/development/mobile/androidenv/default.nix b/pkgs/development/mobile/androidenv/default.nix
index 7d7c92cd0f57..4e9f139b95e9 100644
--- a/pkgs/development/mobile/androidenv/default.nix
+++ b/pkgs/development/mobile/androidenv/default.nix
@@ -25,15 +25,15 @@ rec {
     inherit (pkgs) stdenv fetchurl unzip;
   };
 
-  platforms = if (pkgs.stdenv.system == "i686-linux" || pkgs.stdenv.system == "x86_64-linux")
+  platforms = if (pkgs.stdenv.hostPlatform.system == "i686-linux" || pkgs.stdenv.hostPlatform.system == "x86_64-linux")
     then import ./platforms-linux.nix {
       inherit (pkgs) stdenv fetchurl unzip;
     }
-    else if pkgs.stdenv.system == "x86_64-darwin"
+    else if pkgs.stdenv.hostPlatform.system == "x86_64-darwin"
     then import ./platforms-macosx.nix {
       inherit (pkgs) stdenv fetchurl unzip;
     }
-    else throw "Platform: ${pkgs.stdenv.system} not supported!";
+    else throw "Platform: ${pkgs.stdenv.hostPlatform.system} not supported!";
 
   sysimages = import ./sysimages.nix {
     inherit (pkgs) stdenv fetchurl unzip;
diff --git a/pkgs/development/mobile/androidenv/platform-tools.nix b/pkgs/development/mobile/androidenv/platform-tools.nix
index f5e579942846..22b5cd81f870 100644
--- a/pkgs/development/mobile/androidenv/platform-tools.nix
+++ b/pkgs/development/mobile/androidenv/platform-tools.nix
@@ -8,16 +8,16 @@ in
 stdenv.mkDerivation rec {
   version = "26.0.2";
   name = "android-platform-tools-r${version}";
-  src = if (stdenv.system == "i686-linux" || stdenv.system == "x86_64-linux")
+  src = if (stdenv.hostPlatform.system == "i686-linux" || stdenv.hostPlatform.system == "x86_64-linux")
     then fetchurl {
       url = "https://dl.google.com/android/repository/platform-tools_r${version}-linux.zip";
       sha256 = "0695npvxljbbh8xwfm65k34fcpyfkzvfkssgnp46wkmnq8w5mcb3";
     }
-    else if stdenv.system == "x86_64-darwin" then fetchurl {
+    else if stdenv.hostPlatform.system == "x86_64-darwin" then fetchurl {
       url = "https://dl.google.com/android/repository/platform-tools_r${version}-darwin.zip";
       sha256 = "0gy7apw9pmnnm41z6ywglw5va4ghmny4j57778may4q7ar751l56";
     }
-    else throw "System ${stdenv.system} not supported!";
+    else throw "System ${stdenv.hostPlatform.system} not supported!";
 
   buildCommand = ''
     mkdir -p $out
@@ -25,7 +25,7 @@ stdenv.mkDerivation rec {
     unzip $src
     cd platform-tools
 
-    ${stdenv.lib.optionalString (stdenv.system == "i686-linux" || stdenv.system == "x86_64-linux")
+    ${stdenv.lib.optionalString (stdenv.hostPlatform.system == "i686-linux" || stdenv.hostPlatform.system == "x86_64-linux")
       ''
         for i in adb dmtracedump fastboot hprof-conv sqlite3
         do
diff --git a/pkgs/development/mobile/titaniumenv/build-app.nix b/pkgs/development/mobile/titaniumenv/build-app.nix
index 83bd941e5ffa..0250e5bf2e28 100644
--- a/pkgs/development/mobile/titaniumenv/build-app.nix
+++ b/pkgs/development/mobile/titaniumenv/build-app.nix
@@ -26,7 +26,7 @@ stdenv.mkDerivation {
   name = stdenv.lib.replaceChars [" "] [""] name;
   inherit src;
 
-  buildInputs = [ nodejs titanium alloy jdk python which file ] ++ stdenv.lib.optional (stdenv.system == "x86_64-darwin") xcodewrapper;
+  buildInputs = [ nodejs titanium alloy jdk python which file ] ++ stdenv.lib.optional (stdenv.hostPlatform.system == "x86_64-darwin") xcodewrapper;
   
   buildPhase = ''
     ${preBuild}
diff --git a/pkgs/development/mobile/titaniumenv/default.nix b/pkgs/development/mobile/titaniumenv/default.nix
index b09a483290f7..f411a8d61fd0 100644
--- a/pkgs/development/mobile/titaniumenv/default.nix
+++ b/pkgs/development/mobile/titaniumenv/default.nix
@@ -3,7 +3,7 @@
 rec {
   androidenv = pkgs.androidenv;
 
-  xcodeenv = if pkgs.stdenv.system == "x86_64-darwin" then pkgs.xcodeenv.override {
+  xcodeenv = if pkgs.stdenv.hostPlatform.system == "x86_64-darwin" then pkgs.xcodeenv.override {
     version = xcodeVersion;
     inherit xcodeBaseDir;
   } else null;
diff --git a/pkgs/development/mobile/titaniumenv/titaniumsdk-6.3.nix b/pkgs/development/mobile/titaniumenv/titaniumsdk-6.3.nix
index 26adf373826e..b8c2688708bb 100644
--- a/pkgs/development/mobile/titaniumenv/titaniumsdk-6.3.nix
+++ b/pkgs/development/mobile/titaniumenv/titaniumsdk-6.3.nix
@@ -2,15 +2,15 @@
 
 stdenv.mkDerivation {
   name = "mobilesdk-6.3.1.GA";
-  src = if (stdenv.system == "i686-linux" || stdenv.system == "x86_64-linux") then fetchurl {
+  src = if (stdenv.hostPlatform.system == "i686-linux" || stdenv.hostPlatform.system == "x86_64-linux") then fetchurl {
     url = http://builds.appcelerator.com/mobile/6_3_X/mobilesdk-6.3.1.v20171101154403-linux.zip;
     sha256 = "0g8dqqf5ffa7ll3rqm5naywipnv2vvfxcj9fmqg1wnvvxf0rflqj";
   }
-  else if stdenv.system == "x86_64-darwin" then fetchurl {
+  else if stdenv.hostPlatform.system == "x86_64-darwin" then fetchurl {
     url = http://builds.appcelerator.com/mobile/6_3_X/mobilesdk-6.3.1.v20171101154403-osx.zip;
     sha256 = "00bm8vv70mg4kd7jvmxd1bfqafv6zdpdx816i0hvf801zwnak4nj";
   }
-  else throw "Platform: ${stdenv.system} not supported!";
+  else throw "Platform: ${stdenv.hostPlatform.system} not supported!";
   
   buildInputs = [ unzip makeWrapper ];
   
@@ -23,18 +23,18 @@ stdenv.mkDerivation {
     cd mobilesdk/*
     mv * 6.3.1.GA
     cd *
-    ${stdenv.lib.optionalString (stdenv.system == "x86_64-darwin") ''
+    ${stdenv.lib.optionalString (stdenv.hostPlatform.system == "x86_64-darwin") ''
       # Fixes a bad archive copying error when generating an IPA file
       sed -i -e "s|cp -rf|/bin/cp -rf|" iphone/cli/commands/_build.js
     ''}
 
     # Patch some executables
     
-    ${if stdenv.system == "i686-linux" then
+    ${if stdenv.hostPlatform.system == "i686-linux" then
       ''
         patchelf --set-interpreter ${stdenv.cc.libc}/lib/ld-linux.so.2 android/titanium_prep.linux32
       ''
-      else if stdenv.system == "x86_64-linux" then
+      else if stdenv.hostPlatform.system == "x86_64-linux" then
       ''
         patchelf --set-interpreter ${stdenv.cc.libc}/lib/ld-linux-x86-64.so.2 android/titanium_prep.linux64
       ''
diff --git a/pkgs/development/mobile/titaniumenv/titaniumsdk-7.1.nix b/pkgs/development/mobile/titaniumenv/titaniumsdk-7.1.nix
index a6de1f0ae8c6..4d3bd420969c 100644
--- a/pkgs/development/mobile/titaniumenv/titaniumsdk-7.1.nix
+++ b/pkgs/development/mobile/titaniumenv/titaniumsdk-7.1.nix
@@ -54,15 +54,15 @@ let
 in
 stdenv.mkDerivation {
   name = "mobilesdk-7.1.0.GA";
-  src = if (stdenv.system == "i686-linux" || stdenv.system == "x86_64-linux") then fetchurl {
+  src = if (stdenv.hostPlatform.system == "i686-linux" || stdenv.hostPlatform.system == "x86_64-linux") then fetchurl {
     url = http://builds.appcelerator.com/mobile/7_1_X/mobilesdk-7.1.0.v20180314133955-linux.zip;
     sha256 = "18b3jnr65sdn5wj191bcl48gvhyklxmighxakv4vrz1fb59kyvqn";
   }
-  else if stdenv.system == "x86_64-darwin" then fetchurl {
+  else if stdenv.hostPlatform.system == "x86_64-darwin" then fetchurl {
     url = http://builds.appcelerator.com/mobile/7_1_X/mobilesdk-7.1.0.v20180314133955-osx.zip;
     sha256 = "1f62616biwsw1fqxz2sq7lpa6bsfjazffliplyf5dpnh298cnc1m";
   }
-  else throw "Platform: ${stdenv.system} not supported!";
+  else throw "Platform: ${stdenv.hostPlatform.system} not supported!";
 
   buildInputs = [ unzip makeWrapper ];
 
@@ -89,11 +89,11 @@ stdenv.mkDerivation {
 
     # Patch some executables
 
-    ${if stdenv.system == "i686-linux" then
+    ${if stdenv.hostPlatform.system == "i686-linux" then
       ''
         patchelf --set-interpreter ${stdenv.cc.libc}/lib/ld-linux.so.2 android/titanium_prep.linux32
       ''
-      else if stdenv.system == "x86_64-linux" then
+      else if stdenv.hostPlatform.system == "x86_64-linux" then
       ''
         patchelf --set-interpreter ${stdenv.cc.libc}/lib/ld-linux-x86-64.so.2 android/titanium_prep.linux64
       ''
diff --git a/pkgs/development/node-packages/default-v10.nix b/pkgs/development/node-packages/default-v10.nix
index d7df19066bb3..a438c961513f 100644
--- a/pkgs/development/node-packages/default-v10.nix
+++ b/pkgs/development/node-packages/default-v10.nix
@@ -1,8 +1,9 @@
-{pkgs, system, nodejs, stdenv}:
+{ pkgs, nodejs, stdenv }:
 
 let
   nodePackages = import ./composition-v10.nix {
-    inherit pkgs system nodejs;
+    inherit pkgs nodejs;
+    inherit (stdenv.hostPlatform) system;
   };
 in
 nodePackages // {
diff --git a/pkgs/development/node-packages/default-v6.nix b/pkgs/development/node-packages/default-v6.nix
index 6b508b6f0cce..f4e28d0fd341 100644
--- a/pkgs/development/node-packages/default-v6.nix
+++ b/pkgs/development/node-packages/default-v6.nix
@@ -1,8 +1,9 @@
-{pkgs, system, nodejs, stdenv}:
+{ pkgs, nodejs, stdenv }:
 
 let
   nodePackages = import ./composition-v6.nix {
-    inherit pkgs system nodejs;
+    inherit pkgs nodejs;
+    inherit (stdenv.hostPlatform) system;
   };
 in
 nodePackages // {
diff --git a/pkgs/development/node-packages/default-v8.nix b/pkgs/development/node-packages/default-v8.nix
index 561f43271ffc..7e3691dcecb0 100644
--- a/pkgs/development/node-packages/default-v8.nix
+++ b/pkgs/development/node-packages/default-v8.nix
@@ -1,8 +1,9 @@
-{pkgs, system, nodejs, stdenv}:
+{ pkgs, nodejs, stdenv }:
 
 let
   nodePackages = import ./composition-v8.nix {
-    inherit pkgs system nodejs;
+    inherit pkgs nodejs;
+    inherit (stdenv.hostPlatform) system;
   };
 in
 nodePackages // {
diff --git a/pkgs/development/ruby-modules/testing/stubs.nix b/pkgs/development/ruby-modules/testing/stubs.nix
index 7e6d1102f666..aaab2f689602 100644
--- a/pkgs/development/ruby-modules/testing/stubs.nix
+++ b/pkgs/development/ruby-modules/testing/stubs.nix
@@ -6,7 +6,7 @@ let
     text = (builtins.toJSON (lib.filterAttrs ( n: v: builtins.any (x: x == n) ["name" "system"]) argSet));
     builder = stdenv.shell;
     args = [ "-c" "echo  $(<$textPath) > $out"];
-    system = stdenv.system;
+    system = stdenv.hostPlatform.system;
     passAsFile = ["text"];
   };
   fetchurl = {url?"", urls ? [],...}: "fetchurl:${if urls == [] then url else builtins.head urls}";
diff --git a/pkgs/development/tools/analysis/cov-build/default.nix b/pkgs/development/tools/analysis/cov-build/default.nix
index fef98f1e04aa..bd0a4ee5e40a 100644
--- a/pkgs/development/tools/analysis/cov-build/default.nix
+++ b/pkgs/development/tools/analysis/cov-build/default.nix
@@ -11,7 +11,7 @@ stdenv.mkDerivation rec {
   version = "7.0.2";
 
   src =
-    if stdenv.system == "i686-linux"
+    if stdenv.hostPlatform.system == "i686-linux"
     then requireFile {
       name = "cov-analysis-linux32-${version}.tar.gz";
       sha256 = "0i06wbd7blgx9adh9w09by4i18vwmldfp9ix97a5dph2cjymsviy";
diff --git a/pkgs/development/tools/analysis/valgrind/default.nix b/pkgs/development/tools/analysis/valgrind/default.nix
index cbcfa981b6b5..5734a0f27953 100644
--- a/pkgs/development/tools/analysis/valgrind/default.nix
+++ b/pkgs/development/tools/analysis/valgrind/default.nix
@@ -57,7 +57,7 @@ stdenv.mkDerivation rec {
     '';
 
   configureFlags =
-    stdenv.lib.optional (stdenv.system == "x86_64-linux" || stdenv.system == "x86_64-darwin") "--enable-only64bit";
+    stdenv.lib.optional (stdenv.hostPlatform.system == "x86_64-linux" || stdenv.hostPlatform.system == "x86_64-darwin") "--enable-only64bit";
 
   doCheck = false; # fails
 
diff --git a/pkgs/development/tools/electron/default.nix b/pkgs/development/tools/electron/default.nix
index 695a532305a9..942748a38106 100644
--- a/pkgs/development/tools/electron/default.nix
+++ b/pkgs/development/tools/electron/default.nix
@@ -4,7 +4,7 @@ let
   version = "1.8.2";
   name = "electron-${version}";
 
-  throwSystem = throw "Unsupported system: ${stdenv.system}";
+  throwSystem = throw "Unsupported system: ${stdenv.hostPlatform.system}";
 
   meta = with stdenv.lib; {
     description = "Cross platform desktop application shell";
@@ -34,7 +34,7 @@ let
         url = "https://github.com/electron/electron/releases/download/v${version}/electron-v${version}-linux-arm64.zip";
         sha256 = "0k4np2d4y15x1qfay8y9m8v9y223vdpbq5fdxa3ywbbyf8j361zd";
       };
-    }.${stdenv.system} or throwSystem;
+    }.${stdenv.hostPlatform.system} or throwSystem;
 
     buildInputs = [ unzip makeWrapper ];
 
diff --git a/pkgs/development/tools/github/github-release/default.nix b/pkgs/development/tools/github/github-release/default.nix
index 1ccd1061a136..b80ddff054a9 100644
--- a/pkgs/development/tools/github/github-release/default.nix
+++ b/pkgs/development/tools/github/github-release/default.nix
@@ -1,9 +1,9 @@
 { stdenv, fetchurl }:
 
 let
-  linuxPredicate = stdenv.system == "x86_64-linux";
-  bsdPredicate = stdenv.system == "x86_64-freebsd";
-  darwinPredicate = stdenv.system == "x86_64-darwin";
+  linuxPredicate = stdenv.hostPlatform.system == "x86_64-linux";
+  bsdPredicate = stdenv.hostPlatform.system == "x86_64-freebsd";
+  darwinPredicate = stdenv.hostPlatform.system == "x86_64-darwin";
   metadata = assert linuxPredicate || bsdPredicate || darwinPredicate;
     if linuxPredicate then
       { arch = "linux-amd64";
diff --git a/pkgs/development/tools/google-app-engine-go-sdk/default.nix b/pkgs/development/tools/google-app-engine-go-sdk/default.nix
index c85186e1c0b2..ba4f4bb3f519 100644
--- a/pkgs/development/tools/google-app-engine-go-sdk/default.nix
+++ b/pkgs/development/tools/google-app-engine-go-sdk/default.nix
@@ -6,7 +6,7 @@ stdenv.mkDerivation rec {
   name = "google-app-engine-go-sdk-${version}";
   version = "1.9.61";
   src =
-    if stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchzip {
         url = "https://storage.googleapis.com/appengine-sdks/featured/go_appengine_sdk_linux_amd64-${version}.zip";
         sha256 = "1i2j9ympl1218akwsmm7yb31v0gibgpzlb657bcravi1irfv1hhs";
diff --git a/pkgs/development/tools/misc/cflow/default.nix b/pkgs/development/tools/misc/cflow/default.nix
index 8ec0ecd5785d..16098bda3ee5 100644
--- a/pkgs/development/tools/misc/cflow/default.nix
+++ b/pkgs/development/tools/misc/cflow/default.nix
@@ -17,7 +17,7 @@ stdenv.mkDerivation rec {
   buildInputs = [ gettext ] ++
     # We don't have Emacs/GTK/etc. on {Dar,Cyg}win.
     stdenv.lib.optional
-      (! (stdenv.lib.lists.any (x: stdenv.system == x)
+      (! (stdenv.lib.lists.any (x: stdenv.hostPlatform.system == x)
               [ "i686-cygwin" ]))
       emacs;
 
diff --git a/pkgs/development/tools/misc/iozone/default.nix b/pkgs/development/tools/misc/iozone/default.nix
index 31d70d280e32..1d5da65df7e0 100644
--- a/pkgs/development/tools/misc/iozone/default.nix
+++ b/pkgs/development/tools/misc/iozone/default.nix
@@ -1,15 +1,15 @@
 { stdenv, fetchurl, gnuplot }:
 
 let
-  target = if stdenv.system == "i686-linux" then
+  target = if stdenv.hostPlatform.system == "i686-linux" then
     "linux"
-  else if stdenv.system == "x86_64-linux" then
+  else if stdenv.hostPlatform.system == "x86_64-linux" then
     "linux-AMD64"
-  else if stdenv.system == "x86_64-darwin" then
+  else if stdenv.hostPlatform.system == "x86_64-darwin" then
     "macosx"
-  else if stdenv.system == "aarch64-linux" then
+  else if stdenv.hostPlatform.system == "aarch64-linux" then
     "linux-arm"
-  else throw "Platform ${stdenv.system} not yet supported.";
+  else throw "Platform ${stdenv.hostPlatform.system} not yet supported.";
 in
 
 stdenv.mkDerivation rec {
diff --git a/pkgs/development/tools/misc/kibana/5.x.nix b/pkgs/development/tools/misc/kibana/5.x.nix
index 4aa9dc8b89a0..0529a2764924 100644
--- a/pkgs/development/tools/misc/kibana/5.x.nix
+++ b/pkgs/development/tools/misc/kibana/5.x.nix
@@ -6,7 +6,7 @@ let
   archOverrides = {
     "i686" = "x86";
   };
-  info = splitString "-" stdenv.system;
+  info = splitString "-" stdenv.hostPlatform.system;
   arch = (elemAt info 0);
   elasticArch = archOverrides."${arch}" or arch;
   plat = elemAt info 1;
@@ -21,7 +21,7 @@ in stdenv.mkDerivation rec {
 
   src = fetchurl {
     url = "https://artifacts.elastic.co/downloads/kibana/${name}-${plat}-${elasticArch}.tar.gz";
-    sha256 = shas."${stdenv.system}" or (throw "Unknown architecture");
+    sha256 = shas."${stdenv.hostPlatform.system}" or (throw "Unknown architecture");
   };
 
   buildInputs = [ makeWrapper ];
diff --git a/pkgs/development/tools/misc/kibana/default.nix b/pkgs/development/tools/misc/kibana/default.nix
index 1fd52f435574..72321f560c7f 100644
--- a/pkgs/development/tools/misc/kibana/default.nix
+++ b/pkgs/development/tools/misc/kibana/default.nix
@@ -12,7 +12,7 @@
 with stdenv.lib;
 let
   inherit (builtins) elemAt;
-  info = splitString "-" stdenv.system;
+  info = splitString "-" stdenv.hostPlatform.system;
   arch = elemAt info 0;
   plat = elemAt info 1;
   shas =
@@ -44,7 +44,7 @@ in stdenv.mkDerivation rec {
 
   src = fetchurl {
     url = "https://artifacts.elastic.co/downloads/kibana/${name}-${plat}-${arch}.tar.gz";
-    sha256 = shas."${stdenv.system}" or (throw "Unknown architecture");
+    sha256 = shas."${stdenv.hostPlatform.system}" or (throw "Unknown architecture");
   };
 
   buildInputs = [ makeWrapper ];
diff --git a/pkgs/development/tools/misc/lsof/default.nix b/pkgs/development/tools/misc/lsof/default.nix
index 005fb09fba09..28c2660ac3d7 100644
--- a/pkgs/development/tools/misc/lsof/default.nix
+++ b/pkgs/development/tools/misc/lsof/default.nix
@@ -1,6 +1,6 @@
 { stdenv, fetchurl, buildPackages, ncurses }:
 
-let dialect = with stdenv.lib; last (splitString "-" stdenv.system); in
+let dialect = with stdenv.lib; last (splitString "-" stdenv.hostPlatform.system); in
 
 stdenv.mkDerivation rec {
   name = "lsof-${version}";
diff --git a/pkgs/development/tools/misc/saleae-logic/default.nix b/pkgs/development/tools/misc/saleae-logic/default.nix
index a8183aa4ba08..c89492287db4 100644
--- a/pkgs/development/tools/misc/saleae-logic/default.nix
+++ b/pkgs/development/tools/misc/saleae-logic/default.nix
@@ -27,13 +27,13 @@ stdenv.mkDerivation rec {
   name = "${pname}-${version}";
 
   src =
-    if stdenv.system == "i686-linux" then
+    if stdenv.hostPlatform.system == "i686-linux" then
       fetchurl {
         name = "saleae-logic-${version}-32bit.zip";
         url = "http://downloads.saleae.com/logic/${version}/Logic%20${version}%20(32-bit).zip";
         sha256 = "1dyrj07cgj2fvwi1sk97vady9ri8f8n7mxy9zyzmw9isngs7bmll";
       }
-    else if stdenv.system == "x86_64-linux" then
+    else if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchurl {
         name = "saleae-logic-${version}-64bit.zip";
         url = "http://downloads.saleae.com/logic/${version}/Logic%20${version}%20(64-bit).zip";
diff --git a/pkgs/development/tools/neoload/default.nix b/pkgs/development/tools/neoload/default.nix
index c68c29f86dea..06945f10eb23 100644
--- a/pkgs/development/tools/neoload/default.nix
+++ b/pkgs/development/tools/neoload/default.nix
@@ -34,7 +34,7 @@ in stdenv.mkDerivation rec {
   name = "neoload-4.1.4";
 
   src = fetchurl (
-    if stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "x86_64-linux" then
       { url = http://neoload.installers.neotys.com/documents/download/neoload/v4.1/neoload_4_1_4_linux_x64.sh;
         sha256 = "199jcf5a0nwfm8wfld2rcjgq64g91vvz2bkmki8dxfzf1yasifcd"; }
     else
diff --git a/pkgs/development/tools/node-webkit/nw12.nix b/pkgs/development/tools/node-webkit/nw12.nix
index df7630e2d16f..099e31b8d62d 100644
--- a/pkgs/development/tools/node-webkit/nw12.nix
+++ b/pkgs/development/tools/node-webkit/nw12.nix
@@ -3,7 +3,7 @@
 , gdk_pixbuf, cairo, nss, nspr, gconf, expat, systemd, libcap
 , libnotify}:
 let
-  bits = if stdenv.system == "x86_64-linux" then "x64"
+  bits = if stdenv.hostPlatform.system == "x86_64-linux" then "x64"
          else "ia32";
 
   nwEnv = buildEnv {
diff --git a/pkgs/development/tools/nwjs/default.nix b/pkgs/development/tools/nwjs/default.nix
index 90c377c4472f..bd0c7f5002c3 100644
--- a/pkgs/development/tools/nwjs/default.nix
+++ b/pkgs/development/tools/nwjs/default.nix
@@ -7,7 +7,7 @@
 , sqlite, udev
 }:
 let
-  bits = if stdenv.system == "x86_64-linux" then "x64"
+  bits = if stdenv.hostPlatform.system == "x86_64-linux" then "x64"
          else "ia32";
 
   nwEnv = buildEnv {
diff --git a/pkgs/development/tools/phantomjs/default.nix b/pkgs/development/tools/phantomjs/default.nix
index 51a83760be39..43fdeff9090b 100644
--- a/pkgs/development/tools/phantomjs/default.nix
+++ b/pkgs/development/tools/phantomjs/default.nix
@@ -12,13 +12,13 @@ stdenv.mkDerivation rec {
   # because it has bundled a lot of external libraries (like QT and Webkit)
   # and no easy/nice way to use the system versions of these
 
-  src = if stdenv.system == "i686-linux" then
+  src = if stdenv.hostPlatform.system == "i686-linux" then
           fetchurl {
             url = "https://bitbucket.org/ariya/phantomjs/downloads/${name}-linux-i686.tar.bz2";
             sha256 = "11fzmssz9pqf3arh4f36w06sl2nyz8l9h8iyxyd7w5aqnq5la0j1";
           }
         else
-          if stdenv.system == "x86_64-linux" then
+          if stdenv.hostPlatform.system == "x86_64-linux" then
             fetchurl {
               url = "https://bitbucket.org/ariya/phantomjs/downloads/${name}-linux-x86_64.tar.bz2";
               sha256 = "0fhnqxxsxhy125fmif1lwgnlhfx908spy7fx9mng4w72320n5nd1";
diff --git a/pkgs/development/tools/sauce-connect/default.nix b/pkgs/development/tools/sauce-connect/default.nix
index fe32f7c24506..d5f7c8e6e89f 100644
--- a/pkgs/development/tools/sauce-connect/default.nix
+++ b/pkgs/development/tools/sauce-connect/default.nix
@@ -7,10 +7,10 @@ stdenv.mkDerivation rec {
   version = "4.4.12";
 
   src = fetchurl (
-    if stdenv.system == "x86_64-linux" then {
+    if stdenv.hostPlatform.system == "x86_64-linux" then {
       url = "https://saucelabs.com/downloads/sc-${version}-linux.tar.gz";
       sha256 = "1yqvx64bgiq27hdhwkzgmzyib8pbjn1idpq6783srxq64asf6iyw";
-    } else if stdenv.system == "i686-linux" then {
+    } else if stdenv.hostPlatform.system == "i686-linux" then {
       url = "https://saucelabs.com/downloads/sc-${version}-linux32.tar.gz";
       sha256 = "02kib56lv4lhwkj5r15484lvvbyjvf9ydi5vccsmxgsxrzmddnl6";
     } else {
diff --git a/pkgs/development/tools/selenium/chromedriver/default.nix b/pkgs/development/tools/selenium/chromedriver/default.nix
index 238c3bc704d0..abbd2a9116ca 100644
--- a/pkgs/development/tools/selenium/chromedriver/default.nix
+++ b/pkgs/development/tools/selenium/chromedriver/default.nix
@@ -15,8 +15,8 @@ let
     };
   };
 
-  spec = allSpecs."${stdenv.system}"
-    or (throw "missing chromedriver binary for ${stdenv.system}");
+  spec = allSpecs."${stdenv.hostPlatform.system}"
+    or (throw "missing chromedriver binary for ${stdenv.hostPlatform.system}");
 
   libs = stdenv.lib.makeLibraryPath [
     stdenv.cc.cc.lib
diff --git a/pkgs/development/web/remarkjs/default.nix b/pkgs/development/web/remarkjs/default.nix
index 03cbf74cbad3..22404481f35c 100644
--- a/pkgs/development/web/remarkjs/default.nix
+++ b/pkgs/development/web/remarkjs/default.nix
@@ -13,7 +13,7 @@ let
   
   nodePackages = import ./nodepkgs.nix {
     inherit pkgs;
-    inherit (stdenv) system;
+    inherit (stdenv.hostPlatform) system;
   };
 
 in stdenv.mkDerivation rec {
diff --git a/pkgs/games/andyetitmoves/default.nix b/pkgs/games/andyetitmoves/default.nix
index 092f07737084..97cbe616c57c 100644
--- a/pkgs/games/andyetitmoves/default.nix
+++ b/pkgs/games/andyetitmoves/default.nix
@@ -7,9 +7,9 @@ in
 stdenv.mkDerivation rec {
   name = "${plainName}-${version}";
 
-  src = if stdenv.system == "i686-linux" || stdenv.system == "x86_64-linux"
+  src = if stdenv.hostPlatform.system == "i686-linux" || stdenv.hostPlatform.system == "x86_64-linux"
     then
-      let postfix        = if stdenv.system == "i686-linux" then "i386" else "x86_64";
+      let postfix        = if stdenv.hostPlatform.system == "i686-linux" then "i386" else "x86_64";
           commercialName = "${plainName}-${version}_${postfix}.tar.gz";
           demoUrl        = "http://www.andyetitmoves.net/demo/${plainName}Demo-${version}_${postfix}.tar.gz";
       in
@@ -22,13 +22,13 @@ stdenv.mkDerivation rec {
                  directory where yousaved it.
                '';
                name = commercialName;
-               sha256 = if stdenv.system == "i686-linux"
+               sha256 = if stdenv.hostPlatform.system == "i686-linux"
                           then "15wvzmmidvykwjrbnq70h5jrvnjx1hcrm0357qj85q4aqbzavh01"
                           else "1v8z16qa9ka8sf7qq45knsxj87s6sipvv3a7xq11pb5xk08fb2ql";
              }
         else fetchurl {
                url = demoUrl;
-               sha256 = if stdenv.system == "i686-linux"
+               sha256 = if stdenv.hostPlatform.system == "i686-linux"
                           then "0f14vrrbq05hsbdajrb5y9za65fpng1lc8f0adb4aaz27x7sh525"
                           else "0mg41ya0b27blq3b5498kwl4rj46dj21rcd7qd0rw1kyvr7sx4v4";
              }
diff --git a/pkgs/games/dwarf-fortress/dfhack/default.nix b/pkgs/games/dwarf-fortress/dfhack/default.nix
index a7b059bb6892..4a8c84cf92dc 100644
--- a/pkgs/games/dwarf-fortress/dfhack/default.nix
+++ b/pkgs/games/dwarf-fortress/dfhack/default.nix
@@ -13,8 +13,8 @@ let
   xmlRev = "23500e4e9bd1885365d0a2ef1746c321c1dd5094";
 
   arch =
-    if stdenv.system == "x86_64-linux" then "64"
-    else if stdenv.system == "i686-linux" then "32"
+    if stdenv.hostPlatform.system == "x86_64-linux" then "64"
+    else if stdenv.hostPlatform.system == "i686-linux" then "32"
     else throw "Unsupported architecture";
 
   fakegit = writeScriptBin "git" ''
diff --git a/pkgs/games/dwarf-fortress/game.nix b/pkgs/games/dwarf-fortress/game.nix
index f57e9703fabf..2547bb83f3f5 100644
--- a/pkgs/games/dwarf-fortress/game.nix
+++ b/pkgs/games/dwarf-fortress/game.nix
@@ -33,9 +33,9 @@ let
   game = if hasAttr dfVersion df-hashes
          then getAttr dfVersion df-hashes
          else throw "Unknown Dwarf Fortress version: ${dfVersion}";
-  dfPlatform = if hasAttr stdenv.system platforms
-               then getAttr stdenv.system platforms
-               else throw "Unsupported system: ${stdenv.system}";
+  dfPlatform = if hasAttr stdenv.hostPlatform.system platforms
+               then getAttr stdenv.hostPlatform.system platforms
+               else throw "Unsupported system: ${stdenv.hostPlatform.system}";
   sha256 = if hasAttr dfPlatform game
            then getAttr dfPlatform game
            else throw "Unsupported dfPlatform: ${dfPlatform}";
diff --git a/pkgs/games/eduke32/default.nix b/pkgs/games/eduke32/default.nix
index 733b6070b1fc..502a554bae22 100644
--- a/pkgs/games/eduke32/default.nix
+++ b/pkgs/games/eduke32/default.nix
@@ -15,7 +15,7 @@ in stdenv.mkDerivation rec {
   };
 
   buildInputs = [ flac gtk2 libvorbis libvpx libGLU_combined SDL2 SDL2_mixer ]
-    ++ stdenv.lib.optional (stdenv.system == "i686-linux") nasm;
+    ++ stdenv.lib.optional (stdenv.hostPlatform.system == "i686-linux") nasm;
   nativeBuildInputs = [ pkgconfig ];
 
   postPatch = ''
diff --git a/pkgs/games/ezquake/default.nix b/pkgs/games/ezquake/default.nix
index 14885e7a3b2b..85433e116fbc 100644
--- a/pkgs/games/ezquake/default.nix
+++ b/pkgs/games/ezquake/default.nix
@@ -20,8 +20,8 @@ stdenv.mkDerivation rec {
   ];
 
   installPhase = with stdenv.lib; let
-    sys = last (splitString "-" stdenv.system);
-    arch = head (splitString "-" stdenv.system);
+    sys = last (splitString "-" stdenv.hostPlatform.system);
+    arch = head (splitString "-" stdenv.hostPlatform.system);
   in ''
     mkdir -p $out/bin
     find .
diff --git a/pkgs/games/factorio/default.nix b/pkgs/games/factorio/default.nix
index d0ffa10baeca..bb019e570260 100644
--- a/pkgs/games/factorio/default.nix
+++ b/pkgs/games/factorio/default.nix
@@ -46,7 +46,7 @@ let
       };
     };
   };
-  actual = binDists.${stdenv.system}.${releaseType}.${branch} or (throw "Factorio: unsupported platform");
+  actual = binDists.${stdenv.hostPlatform.system}.${releaseType}.${branch} or (throw "Factorio: unsupported platform");
 
   bdistForArch = arch: { sha256 ? null
                        , version ? "0.16.51"
diff --git a/pkgs/games/nethack/default.nix b/pkgs/games/nethack/default.nix
index 3f9ec93f8618..2a39e3499ed9 100644
--- a/pkgs/games/nethack/default.nix
+++ b/pkgs/games/nethack/default.nix
@@ -6,7 +6,7 @@
 let
   platform =
     if stdenv.hostPlatform.isUnix then "unix"
-    else throw "Unknown platform for NetHack: ${stdenv.system}";
+    else throw "Unknown platform for NetHack: ${stdenv.hostPlatform.system}";
   unixHint =
     if x11Mode then "linux-x11"
     else if qtMode then "linux-qt4"
diff --git a/pkgs/games/oilrush/default.nix b/pkgs/games/oilrush/default.nix
index d637c1595954..319cdb610ca6 100644
--- a/pkgs/games/oilrush/default.nix
+++ b/pkgs/games/oilrush/default.nix
@@ -13,8 +13,8 @@ stdenv.mkDerivation {
     assert url != null && sha256 != null;
     fetchurl { inherit url sha256; };
   shell = stdenv.shell;
-  arch = if stdenv.system == "x86_64-linux" then "x64"
-         else if stdenv.system == "i686-linux" then "x86"
+  arch = if stdenv.hostPlatform.system == "x86_64-linux" then "x64"
+         else if stdenv.hostPlatform.system == "i686-linux" then "x86"
          else "";
   unpackPhase = ''
     mkdir oilrush
diff --git a/pkgs/games/openarena/default.nix b/pkgs/games/openarena/default.nix
index 22ce05cb38a7..19e608f393a1 100644
--- a/pkgs/games/openarena/default.nix
+++ b/pkgs/games/openarena/default.nix
@@ -21,7 +21,7 @@ stdenv.mkDerivation rec {
     cd $out
     unzip $src
 
-    ${if stdenv.system == "x86_64-linux" then ''
+    ${if stdenv.hostPlatform.system == "x86_64-linux" then ''
       patchelf --set-interpreter "${interpreter}" "${gameDir}/openarena.x86_64"
       makeWrapper "${gameDir}/openarena.x86_64" "$out/bin/openarena" \
         --prefix LD_LIBRARY_PATH : "${libPath}"
diff --git a/pkgs/games/racer/default.nix b/pkgs/games/racer/default.nix
index 4cbc5397bb3e..d11315cd6dfa 100644
--- a/pkgs/games/racer/default.nix
+++ b/pkgs/games/racer/default.nix
@@ -3,10 +3,10 @@
 stdenv.mkDerivation rec {
   name = "racer-1.1";
 
-  src = if stdenv.system == "i686-linux" then fetchurl {
+  src = if stdenv.hostPlatform.system == "i686-linux" then fetchurl {
     url = http://hippo.nipax.cz/src/racer-1.1.tar.gz;
     sha256 = "0fll1qkqfcjq87k0jzsilcw701z92lfxn2y5ga1n038772lymxl9";
-  } else if stdenv.system == "x86_64-linux" then fetchurl {
+  } else if stdenv.hostPlatform.system == "x86_64-linux" then fetchurl {
     url = https://hippo.nipax.cz/src/racer-1.1.64.tar.gz;
     sha256 = "0rjy3gmlhwfkb9zs58j0mc0dar0livwpbc19r6zw5r2k6r7xdan0";
   } else
diff --git a/pkgs/games/sdlmame/default.nix b/pkgs/games/sdlmame/default.nix
index fa498b8e0411..9f90c9f14aac 100644
--- a/pkgs/games/sdlmame/default.nix
+++ b/pkgs/games/sdlmame/default.nix
@@ -4,7 +4,7 @@ stdenv.mkDerivation rec {
   version = "0.151.u0-1";
   name    = "sdlmame-${version}";
 
-  src = if stdenv.system == "x86_64-linux"
+  src = if stdenv.hostPlatform.system == "x86_64-linux"
     then fetchurl {
       url    = "http://seblu.net/a/archive/packages/s/sdlmame/${name}-x86_64.pkg.tar.xz";
       sha256 = "1j9vjxhrhsskrlk5wr7al4wk2hh3983kcva42mqal09bmc8qg3m9";
diff --git a/pkgs/games/steam/default.nix b/pkgs/games/steam/default.nix
index b7dbba552698..e8a911bebd5e 100644
--- a/pkgs/games/steam/default.nix
+++ b/pkgs/games/steam/default.nix
@@ -4,9 +4,9 @@ let
   callPackage = newScope self;
 
   self = rec {
-    steamArch = if pkgs.stdenv.system == "x86_64-linux" then "amd64"
-                else if pkgs.stdenv.system == "i686-linux" then "i386"
-                else throw "Unsupported platform: ${pkgs.stdenv.system}";
+    steamArch = if pkgs.stdenv.hostPlatform.system == "x86_64-linux" then "amd64"
+                else if pkgs.stdenv.hostPlatform.system == "i686-linux" then "i386"
+                else throw "Unsupported platform: ${pkgs.stdenv.hostPlatform.system}";
 
     steam-runtime = callPackage ./runtime.nix { };
     steam-runtime-wrapped = callPackage ./runtime-wrapped.nix { };
diff --git a/pkgs/games/ut2004/demo.nix b/pkgs/games/ut2004/demo.nix
index 1a7ea2da75b6..9aea992ac750 100644
--- a/pkgs/games/ut2004/demo.nix
+++ b/pkgs/games/ut2004/demo.nix
@@ -2,8 +2,8 @@
 
 let
   arch =
-    if stdenv.system == "x86_64-linux" then "amd64"
-    else if stdenv.system == "i686-linux" then "x86"
+    if stdenv.hostPlatform.system == "x86_64-linux" then "amd64"
+    else if stdenv.hostPlatform.system == "i686-linux" then "x86"
     else throw "Unsupported architecture";
 
 in stdenv.mkDerivation rec {
diff --git a/pkgs/games/vessel/default.nix b/pkgs/games/vessel/default.nix
index 62feeb97d521..ab6f1ca765ce 100644
--- a/pkgs/games/vessel/default.nix
+++ b/pkgs/games/vessel/default.nix
@@ -15,7 +15,7 @@ stdenv.mkDerivation rec {
       message = goBuyItNow;
       name = "${name}-bin";
       sha256 = "1vpwcrjiln2mx43h7ib3jnccyr3chk7a5x2bw9kb4lw8ycygvg96";
-    } else throw "unsupported platform ${stdenv.system} only i686-linux supported for now.";
+    } else throw "unsupported platform ${stdenv.hostPlatform.system} only i686-linux supported for now.";
 
   phases = "installPhase";
   ld_preload = ./isatty.c;
diff --git a/pkgs/games/worldofgoo/default.nix b/pkgs/games/worldofgoo/default.nix
index 9684f3b876a8..ad86072dd1ca 100644
--- a/pkgs/games/worldofgoo/default.nix
+++ b/pkgs/games/worldofgoo/default.nix
@@ -9,7 +9,7 @@ stdenv.mkDerivation rec {
     then "WorldOfGooDemo-1.41"
     else "WorldofGoo-1.41";
 
-  arch = if stdenv.system == "x86_64-linux" then "supported"
+  arch = if stdenv.hostPlatform.system == "x86_64-linux" then "supported"
     else throw "Sorry. World of Goo only is only supported on x86_64 now.";
 
   goBuyItNow = '' 
diff --git a/pkgs/games/zandronum/fmod.nix b/pkgs/games/zandronum/fmod.nix
index 2c53d93e4011..a5d9098242bd 100644
--- a/pkgs/games/zandronum/fmod.nix
+++ b/pkgs/games/zandronum/fmod.nix
@@ -1,7 +1,7 @@
 { stdenv, lib, fetchurl, alsaLib, libpulseaudio, undmg }:
 
 let
-  bits = stdenv.lib.optionalString (stdenv.system == "x86_64-linux") "64";
+  bits = stdenv.lib.optionalString (stdenv.hostPlatform.system == "x86_64-linux") "64";
   libPath = lib.makeLibraryPath [ stdenv.cc.cc alsaLib libpulseaudio ];
 
 in
diff --git a/pkgs/misc/base16-builder/default.nix b/pkgs/misc/base16-builder/default.nix
index be8d42a4292b..3d713848223b 100644
--- a/pkgs/misc/base16-builder/default.nix
+++ b/pkgs/misc/base16-builder/default.nix
@@ -11,6 +11,6 @@ let
   #
   nodePackages = import ./node-packages.nix {
     inherit pkgs;
-    inherit (stdenv) system;
+    inherit (stdenv.hostPlatform) system;
   };
 in nodePackages.base16-builder
diff --git a/pkgs/misc/cups/drivers/cnijfilter_4_00/default.nix b/pkgs/misc/cups/drivers/cnijfilter_4_00/default.nix
index b83e84154bbe..c8e5ddd09b14 100644
--- a/pkgs/misc/cups/drivers/cnijfilter_4_00/default.nix
+++ b/pkgs/misc/cups/drivers/cnijfilter_4_00/default.nix
@@ -7,9 +7,9 @@
    file included in the tarball */
 
 let arch = 
-  if stdenv.system == "x86_64-linux" then "64"
-    else if stdenv.system == "i686-linux" then "32"
-    else throw "Unsupported system ${stdenv.system}";
+  if stdenv.hostPlatform.system == "x86_64-linux" then "64"
+    else if stdenv.hostPlatform.system == "i686-linux" then "32"
+    else throw "Unsupported system ${stdenv.hostPlatform.system}";
 
 in stdenv.mkDerivation rec {
   name = "cnijfilter-${version}";
diff --git a/pkgs/misc/cups/drivers/kyocera/default.nix b/pkgs/misc/cups/drivers/kyocera/default.nix
index 0711bad86a1e..9b40e4ff50e1 100644
--- a/pkgs/misc/cups/drivers/kyocera/default.nix
+++ b/pkgs/misc/cups/drivers/kyocera/default.nix
@@ -2,9 +2,9 @@
 
 let
   platform =
-    if stdenv.system == "x86_64-linux" then "64bit"
-    else if stdenv.system == "i686-linux" then "32bit"
-         else throw "Unsupported system: ${stdenv.system}";
+    if stdenv.hostPlatform.system == "x86_64-linux" then "64bit"
+    else if stdenv.hostPlatform.system == "i686-linux" then "32bit"
+         else throw "Unsupported system: ${stdenv.hostPlatform.system}";
 
   libPath = lib.makeLibraryPath [ cups ];
 in
diff --git a/pkgs/misc/cups/drivers/kyodialog3/default.nix b/pkgs/misc/cups/drivers/kyodialog3/default.nix
index 073bd4ccbbfc..bcd2914da0ce 100644
--- a/pkgs/misc/cups/drivers/kyodialog3/default.nix
+++ b/pkgs/misc/cups/drivers/kyodialog3/default.nix
@@ -6,9 +6,9 @@
 
 let
   platform =
-    if stdenv.system == "x86_64-linux" then "64bit"
-    else if stdenv.system == "i686-linux" then "32bit"
-         else throw "Unsupported system: ${stdenv.system}";
+    if stdenv.hostPlatform.system == "x86_64-linux" then "64bit"
+    else if stdenv.hostPlatform.system == "i686-linux" then "32bit"
+         else throw "Unsupported system: ${stdenv.hostPlatform.system}";
   debPlatform =
     if platform == "64bit" then "amd64"
     else "i386";
diff --git a/pkgs/misc/cups/drivers/samsung/4.01.17.nix b/pkgs/misc/cups/drivers/samsung/4.01.17.nix
index b30b4c4a2c18..547e25b6514e 100644
--- a/pkgs/misc/cups/drivers/samsung/4.01.17.nix
+++ b/pkgs/misc/cups/drivers/samsung/4.01.17.nix
@@ -16,8 +16,8 @@
 # Do not bump lightly! Visit <http://www.bchemnet.com/suldr/supported.html>
 # to see what will break when upgrading. Consider a new versioned attribute.
 let
-  installationPath = if stdenv.system == "x86_64-linux" then "x86_64" else "i386";
-  appendPath = if stdenv.system == "x86_64-linux" then "64" else "";
+  installationPath = if stdenv.hostPlatform.system == "x86_64-linux" then "x86_64" else "i386";
+  appendPath = if stdenv.hostPlatform.system == "x86_64-linux" then "64" else "";
   libPath = stdenv.lib.makeLibraryPath [ cups libusb ] + ":$out/lib:${stdenv.cc.cc.lib}/lib${appendPath}";
 in stdenv.mkDerivation rec {
   name = "samsung-UnifiedLinuxDriver-${version}";
diff --git a/pkgs/misc/cups/drivers/samsung/default.nix b/pkgs/misc/cups/drivers/samsung/default.nix
index 48636e1f76aa..b2c4bbb0f203 100644
--- a/pkgs/misc/cups/drivers/samsung/default.nix
+++ b/pkgs/misc/cups/drivers/samsung/default.nix
@@ -2,7 +2,7 @@
 
 let
 
-    arch = if stdenv.system == "x86_64-linux"
+    arch = if stdenv.hostPlatform.system == "x86_64-linux"
       then "x86_64"
       else "i386";
 
diff --git a/pkgs/misc/drivers/gutenprint/bin.nix b/pkgs/misc/drivers/gutenprint/bin.nix
index 3832c4de2dcc..6cf754192f86 100644
--- a/pkgs/misc/drivers/gutenprint/bin.nix
+++ b/pkgs/misc/drivers/gutenprint/bin.nix
@@ -27,7 +27,7 @@ TODO tidy this all up. Find source instead of binary. Fix paths ... Find out how
 stdenv.mkDerivation {
   name = "cups-gutenprint-binary-5.0.1";
 
-  src = if stdenv.system == "x86_64-linux" then fetchurl {
+  src = if stdenv.hostPlatform.system == "x86_64-linux" then fetchurl {
     url = https://www.openprinting.org/download/printdriver/debian/dists/lsb3.1/main/binary-amd64/gutenprint_5.0.1-1lsb3.1_amd64.deb;
     sha256 = "0an5gba6r6v54r53s2gj2fjk8fzpl4lrksjas2333528b0k8gbbc";
   } else throw "TODO"; # get from openprint.com -> drivers -> gutenprint
diff --git a/pkgs/misc/drivers/hplip/3.16.11.nix b/pkgs/misc/drivers/hplip/3.16.11.nix
index 91dce834a4bd..8982834d9a99 100644
--- a/pkgs/misc/drivers/hplip/3.16.11.nix
+++ b/pkgs/misc/drivers/hplip/3.16.11.nix
@@ -34,15 +34,15 @@ let
     "armv7l-linux" = "arm32";
   };
 
-  hplipArch = hplipPlatforms."${stdenv.system}"
-    or (throw "HPLIP not supported on ${stdenv.system}");
+  hplipArch = hplipPlatforms."${stdenv.hostPlatform.system}"
+    or (throw "HPLIP not supported on ${stdenv.hostPlatform.system}");
 
   pluginArches = [ "x86_32" "x86_64" "arm32" ];
 
 in
 
 assert withPlugin -> builtins.elem hplipArch pluginArches
-  || throw "HPLIP plugin not supported on ${stdenv.system}";
+  || throw "HPLIP plugin not supported on ${stdenv.hostPlatform.system}";
 
 pythonPackages.buildPythonApplication {
   inherit name src;
diff --git a/pkgs/misc/drivers/hplip/default.nix b/pkgs/misc/drivers/hplip/default.nix
index 59a75dab8832..f03d75dfa02d 100644
--- a/pkgs/misc/drivers/hplip/default.nix
+++ b/pkgs/misc/drivers/hplip/default.nix
@@ -36,15 +36,15 @@ let
     "armv7l-linux" = "arm32";
   };
 
-  hplipArch = hplipPlatforms."${stdenv.system}"
-    or (throw "HPLIP not supported on ${stdenv.system}");
+  hplipArch = hplipPlatforms."${stdenv.hostPlatform.system}"
+    or (throw "HPLIP not supported on ${stdenv.hostPlatform.system}");
 
   pluginArches = [ "x86_32" "x86_64" "arm32" ];
 
 in
 
 assert withPlugin -> builtins.elem hplipArch pluginArches
-  || throw "HPLIP plugin not supported on ${stdenv.system}";
+  || throw "HPLIP plugin not supported on ${stdenv.hostPlatform.system}";
 
 pythonPackages.buildPythonApplication {
   inherit name src;
diff --git a/pkgs/misc/emulators/retroarch/cores.nix b/pkgs/misc/emulators/retroarch/cores.nix
index 8f6e66c18c39..371ace848fb7 100644
--- a/pkgs/misc/emulators/retroarch/cores.nix
+++ b/pkgs/misc/emulators/retroarch/cores.nix
@@ -272,7 +272,7 @@ in with stdenv.lib.licenses;
 
     extraBuildInputs = [ libGLU_combined libpng ];
   }).override {
-    buildPhase = "make WITH_DYNAREC=${if stdenv.system == "x86_64-linux" then "x86_64" else "x86"}";
+    buildPhase = "make WITH_DYNAREC=${if stdenv.hostPlatform.system == "x86_64-linux" then "x86_64" else "x86"}";
   };
 
   nestopia = (mkLibRetroCore rec {
@@ -300,7 +300,7 @@ in with stdenv.lib.licenses;
 
     extraBuildInputs = [ libGLU_combined libpng ];
   }).override {
-    buildPhase = "make WITH_DYNAREC=${if stdenv.system == "x86_64-linux" then "x86_64" else "x86"}";
+    buildPhase = "make WITH_DYNAREC=${if stdenv.hostPlatform.system == "x86_64-linux" then "x86_64" else "x86"}";
   };
 
   picodrive = (mkLibRetroCore rec {
diff --git a/pkgs/misc/emulators/wine/default.nix b/pkgs/misc/emulators/wine/default.nix
index a8eacbe234c6..91323ab6de7f 100644
--- a/pkgs/misc/emulators/wine/default.nix
+++ b/pkgs/misc/emulators/wine/default.nix
@@ -6,9 +6,9 @@
 # };
 # Make additional configurations on demand:
 # wine.override { wineBuild = "wine32"; wineRelease = "staging"; };
-{ lib, system, callPackage,
+{ lib, stdenv, callPackage,
   wineRelease ? "stable",
-  wineBuild ? (if system == "x86_64-linux" then "wineWow" else "wine32"),
+  wineBuild ? if stdenv.hostPlatform.system == "x86_64-linux" then "wineWow" else "wine32",
   libtxc_dxtn_Name ? "libtxc_dxtn_s2tc",
   pngSupport ? false,
   jpegSupport ? false,
diff --git a/pkgs/os-specific/linux/alsa-plugins/wrapper.nix b/pkgs/os-specific/linux/alsa-plugins/wrapper.nix
index 7dbd01bf058e..60262a14c9b2 100644
--- a/pkgs/os-specific/linux/alsa-plugins/wrapper.nix
+++ b/pkgs/os-specific/linux/alsa-plugins/wrapper.nix
@@ -1,5 +1,5 @@
 { writeScriptBin, stdenv, alsaPlugins }:
-writeScriptBin "ap${if stdenv.system == "i686-linux" then "32" else "64"}" ''
+writeScriptBin "ap${if stdenv.hostPlatform.system == "i686-linux" then "32" else "64"}" ''
   #/bin/sh
   ALSA_PLUGIN_DIRS=${alsaPlugins}/lib/alsa-lib "$@"
 ''
diff --git a/pkgs/os-specific/linux/amdgpu-pro/default.nix b/pkgs/os-specific/linux/amdgpu-pro/default.nix
index 97658c831eb0..b72944a49eb1 100644
--- a/pkgs/os-specific/linux/amdgpu-pro/default.nix
+++ b/pkgs/os-specific/linux/amdgpu-pro/default.nix
@@ -16,9 +16,9 @@ let
   bitness = if stdenv.is64bit then "64" else "32";
 
   libArch =
-    if stdenv.system == "i686-linux" then
+    if stdenv.hostPlatform.system == "i686-linux" then
       "i386-linux-gnu"
-    else if stdenv.system == "x86_64-linux" then
+    else if stdenv.hostPlatform.system == "x86_64-linux" then
       "x86_64-linux-gnu"
     else throw "amdgpu-pro is Linux only. Sorry. The build was stopped.";
 
diff --git a/pkgs/os-specific/linux/ati-drivers/default.nix b/pkgs/os-specific/linux/ati-drivers/default.nix
index df6fa3555fee..d5d42faa913e 100644
--- a/pkgs/os-specific/linux/ati-drivers/default.nix
+++ b/pkgs/os-specific/linux/ati-drivers/default.nix
@@ -37,9 +37,9 @@ stdenv.mkDerivation rec {
   build = "15.302";
 
   linuxonly =
-    if stdenv.system == "i686-linux" then
+    if stdenv.hostPlatform.system == "i686-linux" then
       true
-    else if stdenv.system == "x86_64-linux" then
+    else if stdenv.hostPlatform.system == "x86_64-linux" then
       true
     else throw "ati-drivers are Linux only. Sorry. The build was stopped.";
 
diff --git a/pkgs/os-specific/linux/broadcom-sta/default.nix b/pkgs/os-specific/linux/broadcom-sta/default.nix
index 9848882f3b86..541539522f85 100644
--- a/pkgs/os-specific/linux/broadcom-sta/default.nix
+++ b/pkgs/os-specific/linux/broadcom-sta/default.nix
@@ -7,7 +7,7 @@ let
     x86_64-linux = "1gj485qqr190idilacpxwgqyw21il03zph2rddizgj7fbd6pfyaz";
   };
 
-  arch = stdenv.lib.optionalString (stdenv.system == "x86_64-linux") "_64";
+  arch = stdenv.lib.optionalString (stdenv.hostPlatform.system == "x86_64-linux") "_64";
   tarballVersion = stdenv.lib.replaceStrings ["."] ["_"] version;
   tarball = "hybrid-v35${arch}-nodebug-pcoem-${tarballVersion}.tar.gz";
 in
@@ -16,7 +16,7 @@ stdenv.mkDerivation {
 
   src = fetchurl {
     url = "https://docs.broadcom.com/docs-and-downloads/docs/linux_sta/${tarball}";
-    sha256 = hashes.${stdenv.system} or (throw "Unsupported system: ${stdenv.system}");
+    sha256 = hashes.${stdenv.hostPlatform.system} or (throw "Unsupported system: ${stdenv.hostPlatform.system}");
   };
 
   hardeningDisable = [ "pic" ];
diff --git a/pkgs/os-specific/linux/displaylink/default.nix b/pkgs/os-specific/linux/displaylink/default.nix
index ad42590ad19c..af8c790e325f 100644
--- a/pkgs/os-specific/linux/displaylink/default.nix
+++ b/pkgs/os-specific/linux/displaylink/default.nix
@@ -3,8 +3,8 @@
 
 let
   arch =
-    if stdenv.system == "x86_64-linux" then "x64"
-    else if stdenv.system == "i686-linux" then "x86"
+    if stdenv.hostPlatform.system == "x86_64-linux" then "x64"
+    else if stdenv.hostPlatform.system == "i686-linux" then "x86"
     else throw "Unsupported architecture";
   bins = "${arch}-ubuntu-1604";
   libPath = lib.makeLibraryPath [ stdenv.cc.cc utillinux libusb1 evdi ];
diff --git a/pkgs/os-specific/linux/fusionio/util.nix b/pkgs/os-specific/linux/fusionio/util.nix
index 0f1e2748c889..6327a95f39d7 100644
--- a/pkgs/os-specific/linux/fusionio/util.nix
+++ b/pkgs/os-specific/linux/fusionio/util.nix
@@ -39,7 +39,7 @@ stdenv.mkDerivation {
     description = "Fusionio command line utilities";
     license = licenses.unfree;
     platforms = [ "x86_64-linux" ];
-    broken = stdenv.system != "x86_64-linux";
+    broken = stdenv.hostPlatform.system != "x86_64-linux";
     maintainers = with maintainers; [ wkennington ];
   };
 }
diff --git a/pkgs/os-specific/linux/fusionio/vsl.nix b/pkgs/os-specific/linux/fusionio/vsl.nix
index 665c4b4d0813..6ebe2e0cdaf5 100644
--- a/pkgs/os-specific/linux/fusionio/vsl.nix
+++ b/pkgs/os-specific/linux/fusionio/vsl.nix
@@ -33,7 +33,7 @@ stdenv.mkDerivation rec {
     description = "Kernel driver for accessing fusion-io cards";
     license = licenses.unfree;
     platforms = [ "x86_64-linux" ];
-    broken = stdenv.system != "x86_64-linux";
+    broken = stdenv.hostPlatform.system != "x86_64-linux";
     maintainers = with maintainers; [ wkennington ];
   };
 }
diff --git a/pkgs/os-specific/linux/kernel/common-config.nix b/pkgs/os-specific/linux/kernel/common-config.nix
index bf99729b33e3..27a615d7bb96 100644
--- a/pkgs/os-specific/linux/kernel/common-config.nix
+++ b/pkgs/os-specific/linux/kernel/common-config.nix
@@ -114,7 +114,7 @@ let
       IP_DCCP_CCID3      = no; # experimental
       CLS_U32_PERF       = yes;
       CLS_U32_MARK       = yes;
-      BPF_JIT            = when (stdenv.system == "x86_64-linux") yes;
+      BPF_JIT            = when (stdenv.hostPlatform.system == "x86_64-linux") yes;
       WAN                = yes;
       # Required by systemd per-cgroup firewalling
       CGROUP_BPF                  = option yes;
@@ -184,7 +184,7 @@ let
       FB_VESA             = yes;
       FRAMEBUFFER_CONSOLE = yes;
       FRAMEBUFFER_CONSOLE_ROTATION = yes;
-      FB_GEODE            = when (stdenv.system == "i686-linux") yes;
+      FB_GEODE            = when (stdenv.hostPlatform.system == "i686-linux") yes;
     };
 
     video = {
@@ -497,7 +497,7 @@ let
     };
 
     # Support x2APIC (which requires IRQ remapping)
-    x2apic = optionalAttrs (stdenv.system == "x86_64-linux") {
+    x2apic = optionalAttrs (stdenv.hostPlatform.system == "x86_64-linux") {
       X86_X2APIC = yes;
       IRQ_REMAP  = yes;
     };
diff --git a/pkgs/os-specific/linux/kernel/linux-rpi.nix b/pkgs/os-specific/linux/kernel/linux-rpi.nix
index e68a0ed26719..203faed05444 100644
--- a/pkgs/os-specific/linux/kernel/linux-rpi.nix
+++ b/pkgs/os-specific/linux/kernel/linux-rpi.nix
@@ -18,7 +18,7 @@ stdenv.lib.overrideDerivation (buildLinux (args // rec {
   defconfig = {
     "armv6l-linux" = "bcmrpi_defconfig";
     "armv7l-linux" = "bcm2709_defconfig";
-  }.${stdenv.system} or (throw "linux_rpi not supported on '${stdenv.system}'");
+  }.${stdenv.hostPlatform.system} or (throw "linux_rpi not supported on '${stdenv.hostPlatform.system}'");
 
   features = {
     efiBootStub = false;
diff --git a/pkgs/os-specific/linux/nvidia-x11/generic.nix b/pkgs/os-specific/linux/nvidia-x11/generic.nix
index 0ededc08050d..06125787a588 100644
--- a/pkgs/os-specific/linux/nvidia-x11/generic.nix
+++ b/pkgs/os-specific/linux/nvidia-x11/generic.nix
@@ -34,22 +34,22 @@ let
     builder = ./builder.sh;
 
     src =
-      if stdenv.system == "i686-linux" then
+      if stdenv.hostPlatform.system == "i686-linux" then
         fetchurl {
           url = "https://download.nvidia.com/XFree86/Linux-x86/${version}/NVIDIA-Linux-x86-${version}${pkgSuffix}.run";
           sha256 = sha256_32bit;
         }
-      else if stdenv.system == "x86_64-linux" then
+      else if stdenv.hostPlatform.system == "x86_64-linux" then
         fetchurl {
           url = "https://download.nvidia.com/XFree86/Linux-x86_64/${version}/NVIDIA-Linux-x86_64-${version}${pkgSuffix}.run";
           sha256 = sha256_64bit;
         }
-      else throw "nvidia-x11 does not support platform ${stdenv.system}";
+      else throw "nvidia-x11 does not support platform ${stdenv.hostPlatform.system}";
 
     patches = if libsOnly then null else patches;
     inherit prePatch;
     inherit version useGLVND useProfiles;
-    inherit (stdenv) system;
+    inherit (stdenv.hostPlatform) system;
 
     outputs = [ "out" ] ++ optional (!libsOnly) "bin";
     outputDev = if libsOnly then null else "bin";
diff --git a/pkgs/os-specific/linux/prl-tools/default.nix b/pkgs/os-specific/linux/prl-tools/default.nix
index be93ff6f2eb9..1a4919a5d9d4 100644
--- a/pkgs/os-specific/linux/prl-tools/default.nix
+++ b/pkgs/os-specific/linux/prl-tools/default.nix
@@ -10,8 +10,8 @@ assert kernel != null -> stdenv.lib.versionOlder kernel.version "4.15";
 
 let xorgFullVer = (builtins.parseDrvName xorg.xorgserver.name).version;
     xorgVer = lib.concatStringsSep "." (lib.take 2 (lib.splitString "." xorgFullVer));
-    x64 = if stdenv.system == "x86_64-linux" then true
-          else if stdenv.system == "i686-linux" then false
+    x64 = if stdenv.hostPlatform.system == "x86_64-linux" then true
+          else if stdenv.hostPlatform.system == "i686-linux" then false
           else throw "Parallels Tools for Linux only support {x86-64,i686}-linux targets";
 in
 stdenv.mkDerivation rec {
diff --git a/pkgs/stdenv/generic/make-derivation.nix b/pkgs/stdenv/generic/make-derivation.nix
index 560aa72eb392..8af6d0e04008 100644
--- a/pkgs/stdenv/generic/make-derivation.nix
+++ b/pkgs/stdenv/generic/make-derivation.nix
@@ -187,7 +187,7 @@ rec {
           builder = attrs.realBuilder or stdenv.shell;
           args = attrs.args or ["-e" (attrs.builder or ./default-builder.sh)];
           inherit stdenv;
-          inherit (stdenv) system;
+          inherit (stdenv.hostPlatform) system;
           userHook = config.stdenv.userHook or null;
           __ignoreNulls = true;
 
diff --git a/pkgs/tools/X11/xwinwrap/default.nix b/pkgs/tools/X11/xwinwrap/default.nix
index cc2eb50ce1fd..dbbdb0c04e91 100644
--- a/pkgs/tools/X11/xwinwrap/default.nix
+++ b/pkgs/tools/X11/xwinwrap/default.nix
@@ -16,11 +16,11 @@ stdenv.mkDerivation {
     xlibsWrapper
   ];
 
-  buildPhase = if stdenv.system == "x86_64-linux" then ''
+  buildPhase = if stdenv.hostPlatform.system == "x86_64-linux" then ''
     make all64
-  '' else if stdenv.system == "i686-linux" then ''
+  '' else if stdenv.hostPlatform.system == "i686-linux" then ''
     make all32
-  '' else throw "xwinwrap is not supported on ${stdenv.system}";
+  '' else throw "xwinwrap is not supported on ${stdenv.hostPlatform.system}";
 
   installPhase = ''
     mkdir -p $out/bin
diff --git a/pkgs/tools/admin/bluemix-cli/default.nix b/pkgs/tools/admin/bluemix-cli/default.nix
index 7ae54aab4b9d..8b6395d85d04 100644
--- a/pkgs/tools/admin/bluemix-cli/default.nix
+++ b/pkgs/tools/admin/bluemix-cli/default.nix
@@ -5,7 +5,7 @@ stdenv.mkDerivation rec {
   version = "0.8.0";
 
   src =
-    if stdenv.system == "i686-linux" then
+    if stdenv.hostPlatform.system == "i686-linux" then
       fetchurl {
         name = "linux32-${version}.tar.gz";
         url = "https://clis.ng.bluemix.net/download/bluemix-cli/${version}/linux32";
diff --git a/pkgs/tools/admin/google-cloud-sdk/default.nix b/pkgs/tools/admin/google-cloud-sdk/default.nix
index c2f73cea9558..8b98636b3475 100644
--- a/pkgs/tools/admin/google-cloud-sdk/default.nix
+++ b/pkgs/tools/admin/google-cloud-sdk/default.nix
@@ -32,7 +32,7 @@ in stdenv.mkDerivation rec {
   name = "google-cloud-sdk-${version}";
   version = "206.0.0";
 
-  src = fetchurl (sources name stdenv.system);
+  src = fetchurl (sources name stdenv.hostPlatform.system);
 
   buildInputs = [ python makeWrapper ];
 
diff --git a/pkgs/tools/archivers/gnutar/default.nix b/pkgs/tools/archivers/gnutar/default.nix
index 7532cd899cc6..0cde72069848 100644
--- a/pkgs/tools/archivers/gnutar/default.nix
+++ b/pkgs/tools/archivers/gnutar/default.nix
@@ -30,7 +30,7 @@ stdenv.mkDerivation rec {
 
   # May have some issues with root compilation because the bootstrap tool
   # cannot be used as a login shell for now.
-  FORCE_UNSAFE_CONFIGURE = stdenv.lib.optionalString (stdenv.system == "armv7l-linux" || stdenv.isSunOS) "1";
+  FORCE_UNSAFE_CONFIGURE = stdenv.lib.optionalString (stdenv.hostPlatform.system == "armv7l-linux" || stdenv.isSunOS) "1";
 
   preConfigure = if stdenv.isCygwin then ''
     sed -i gnu/fpending.h -e 's,include <stdio_ext.h>,,'
diff --git a/pkgs/tools/bootloaders/refind/default.nix b/pkgs/tools/bootloaders/refind/default.nix
index 73463bbef897..5f4d77e34b6a 100644
--- a/pkgs/tools/bootloaders/refind/default.nix
+++ b/pkgs/tools/bootloaders/refind/default.nix
@@ -7,7 +7,7 @@ let
   };
 
   inherit
-    (archids.${stdenv.system} or (throw "unsupported system: ${stdenv.system}"))
+    (archids.${stdenv.hostPlatform.system} or (throw "unsupported system: ${stdenv.hostPlatform.system}"))
     hostarch efiPlatform;
 in
 
diff --git a/pkgs/tools/compression/bzip2/default.nix b/pkgs/tools/compression/bzip2/default.nix
index 4b127417ca8d..4a2ba2fcb94c 100644
--- a/pkgs/tools/compression/bzip2/default.nix
+++ b/pkgs/tools/compression/bzip2/default.nix
@@ -1,5 +1,5 @@
 { stdenv, fetchurl
-, linkStatic ? (stdenv.system == "i686-cygwin")
+, linkStatic ? (stdenv.hostPlatform.system == "i686-cygwin")
 }:
 
 stdenv.mkDerivation rec {
diff --git a/pkgs/tools/filesystems/sshfs-fuse/default.nix b/pkgs/tools/filesystems/sshfs-fuse/default.nix
index 183cfb2ddbe4..ddec6b7eff89 100644
--- a/pkgs/tools/filesystems/sshfs-fuse/default.nix
+++ b/pkgs/tools/filesystems/sshfs-fuse/default.nix
@@ -19,7 +19,7 @@ stdenv.mkDerivation rec {
   checkInputs = [ which python3Packages.pytest ];
 
   NIX_CFLAGS_COMPILE = stdenv.lib.optional
-    (stdenv.system == "i686-linux")
+    (stdenv.hostPlatform.system == "i686-linux")
     "-D_FILE_OFFSET_BITS=64";
 
   postInstall = ''
diff --git a/pkgs/tools/graphics/pngout/default.nix b/pkgs/tools/graphics/pngout/default.nix
index afc1a2519fe1..333e5f600765 100644
--- a/pkgs/tools/graphics/pngout/default.nix
+++ b/pkgs/tools/graphics/pngout/default.nix
@@ -1,9 +1,9 @@
 {stdenv, fetchurl}:
 
 let
-  folder = if stdenv.system == "i686-linux" then "i686"
-  else if stdenv.system == "x86_64-linux" then "x86_64"
-  else throw "Unsupported system: ${stdenv.system}";
+  folder = if stdenv.hostPlatform.system == "i686-linux" then "i686"
+  else if stdenv.hostPlatform.system == "x86_64-linux" then "x86_64"
+  else throw "Unsupported system: ${stdenv.hostPlatform.system}";
 in
 stdenv.mkDerivation {
   name = "pngout-20130221";
@@ -17,9 +17,9 @@ stdenv.mkDerivation {
     mkdir -p $out/bin
     cp ${folder}/pngout $out/bin
     
-    ${if stdenv.system == "i686-linux" then ''
+    ${if stdenv.hostPlatform.system == "i686-linux" then ''
         patchelf --set-interpreter ${stdenv.glibc.out}/lib/ld-linux.so.2 $out/bin/pngout
-      '' else if stdenv.system == "x86_64-linux" then ''
+      '' else if stdenv.hostPlatform.system == "x86_64-linux" then ''
         patchelf --set-interpreter ${stdenv.glibc.out}/lib/ld-linux-x86-64.so.2 $out/bin/pngout
       '' else ""}
   '';
diff --git a/pkgs/tools/misc/bandwidth/default.nix b/pkgs/tools/misc/bandwidth/default.nix
index e8ea9117bc5a..e50faaca8995 100644
--- a/pkgs/tools/misc/bandwidth/default.nix
+++ b/pkgs/tools/misc/bandwidth/default.nix
@@ -2,11 +2,11 @@
 
 let
   arch =
-    if      stdenv.system == "x86_64-linux" then "bandwidth64"
-    else if stdenv.system == "i686-linux" then "bandwidth32"
-    else if stdenv.system == "x86_64-darwin" then "bandwidth-mac64"
-    else if stdenv.system == "i686-darwin" then "bandwidth-mac32"
-    else if stdenv.system == "i686-cygwin" then "bandwidth-win32"
+    if      stdenv.hostPlatform.system == "x86_64-linux" then "bandwidth64"
+    else if stdenv.hostPlatform.system == "i686-linux" then "bandwidth32"
+    else if stdenv.hostPlatform.system == "x86_64-darwin" then "bandwidth-mac64"
+    else if stdenv.hostPlatform.system == "i686-darwin" then "bandwidth-mac32"
+    else if stdenv.hostPlatform.system == "i686-cygwin" then "bandwidth-win32"
     else throw "Unknown architecture";
 in
 stdenv.mkDerivation rec {
diff --git a/pkgs/tools/misc/execline/default.nix b/pkgs/tools/misc/execline/default.nix
index 0b606882a5c3..360808f4280b 100644
--- a/pkgs/tools/misc/execline/default.nix
+++ b/pkgs/tools/misc/execline/default.nix
@@ -32,7 +32,7 @@ in stdenv.mkDerivation rec {
     "--with-dynlib=${skalibs.lib}/lib"
   ]
   ++ (if stdenv.isDarwin then [ "--disable-shared" ] else [ "--enable-shared" ])
-  ++ (stdenv.lib.optional stdenv.isDarwin "--build=${stdenv.system}");
+  ++ (stdenv.lib.optional stdenv.isDarwin "--build=${stdenv.hostPlatform.system}");
 
   postInstall = ''
     mkdir -p $doc/share/doc/execline
diff --git a/pkgs/tools/misc/grub/2.0x.nix b/pkgs/tools/misc/grub/2.0x.nix
index 63511782f00b..481a07ef491b 100644
--- a/pkgs/tools/misc/grub/2.0x.nix
+++ b/pkgs/tools/misc/grub/2.0x.nix
@@ -28,8 +28,8 @@ let
     "aarch64-linux".target = "arm64";
   };
 
-  canEfi = any (system: stdenv.system == system) (mapAttrsToList (name: _: name) efiSystemsBuild);
-  inPCSystems = any (system: stdenv.system == system) (mapAttrsToList (name: _: name) pcSystems);
+  canEfi = any (system: stdenv.hostPlatform.system == system) (mapAttrsToList (name: _: name) efiSystemsBuild);
+  inPCSystems = any (system: stdenv.hostPlatform.system == system) (mapAttrsToList (name: _: name) pcSystems);
 
   version = "2.02";
 
@@ -86,14 +86,14 @@ stdenv.mkDerivation rec {
 
   configureFlags = [ "--enable-grub-mount" ] # dep of os-prober
     ++ optional zfsSupport "--enable-libzfs"
-    ++ optionals efiSupport [ "--with-platform=efi" "--target=${efiSystemsBuild.${stdenv.system}.target}" "--program-prefix=" ]
-    ++ optionals xenSupport [ "--with-platform=xen" "--target=${efiSystemsBuild.${stdenv.system}.target}"];
+    ++ optionals efiSupport [ "--with-platform=efi" "--target=${efiSystemsBuild.${stdenv.hostPlatform.system}.target}" "--program-prefix=" ]
+    ++ optionals xenSupport [ "--with-platform=xen" "--target=${efiSystemsBuild.${stdenv.hostPlatform.system}.target}"];
 
   # save target that grub is compiled for
   grubTarget = if efiSupport
-               then "${efiSystemsInstall.${stdenv.system}.target}-efi"
+               then "${efiSystemsInstall.${stdenv.hostPlatform.system}.target}-efi"
                else if inPCSystems
-                    then "${pcSystems.${stdenv.system}.target}-pc"
+                    then "${pcSystems.${stdenv.hostPlatform.system}.target}-pc"
                     else "";
 
   doCheck = false;
diff --git a/pkgs/tools/misc/grub/pvgrub_image/default.nix b/pkgs/tools/misc/grub/pvgrub_image/default.nix
index df5e3f15e95a..19d8afb18575 100644
--- a/pkgs/tools/misc/grub/pvgrub_image/default.nix
+++ b/pkgs/tools/misc/grub/pvgrub_image/default.nix
@@ -22,11 +22,11 @@ stdenv.mkDerivation rec {
     tar -cf memdisk.tar grub.cfg
     # We include all modules except all_video.mod as otherwise grub will fail printing "no symbol table"
     # if we include it.
-    grub-mkimage -O "${efiSystemsBuild.${stdenv.system}.target}-xen" -c grub-bootstrap.cfg \
-      -m memdisk.tar -o "grub-${efiSystemsBuild.${stdenv.system}.target}-xen.bin" \
-      $(ls "${grub2_xen}/lib/grub/${efiSystemsBuild.${stdenv.system}.target}-xen/" |grep 'mod''$'|grep -v '^all_video\.mod''$')
+    grub-mkimage -O "${efiSystemsBuild.${stdenv.hostPlatform.system}.target}-xen" -c grub-bootstrap.cfg \
+      -m memdisk.tar -o "grub-${efiSystemsBuild.${stdenv.hostPlatform.system}.target}-xen.bin" \
+      $(ls "${grub2_xen}/lib/grub/${efiSystemsBuild.${stdenv.hostPlatform.system}.target}-xen/" |grep 'mod''$'|grep -v '^all_video\.mod''$')
     mkdir -p "$out/lib/grub-xen"
-    cp "grub-${efiSystemsBuild.${stdenv.system}.target}-xen.bin" $out/lib/grub-xen/
+    cp "grub-${efiSystemsBuild.${stdenv.hostPlatform.system}.target}-xen.bin" $out/lib/grub-xen/
   '';
 
   meta = with stdenv.lib; {
diff --git a/pkgs/tools/misc/grub/trusted.nix b/pkgs/tools/misc/grub/trusted.nix
index 63a73658e0ac..0e867d7cffd0 100644
--- a/pkgs/tools/misc/grub/trusted.nix
+++ b/pkgs/tools/misc/grub/trusted.nix
@@ -10,7 +10,7 @@ let
     "x86_64-linux".target = "i386";
   };
 
-  inPCSystems = any (system: stdenv.system == system) (mapAttrsToList (name: _: name) pcSystems);
+  inPCSystems = any (system: stdenv.hostPlatform.system == system) (mapAttrsToList (name: _: name) pcSystems);
 
   version = if for_HP_laptop then "1.2.1" else "1.2.0";
 
@@ -84,7 +84,7 @@ stdenv.mkDerivation rec {
 
   # save target that grub is compiled for
   grubTarget = if inPCSystems
-               then "${pcSystems.${stdenv.system}.target}-pc"
+               then "${pcSystems.${stdenv.hostPlatform.system}.target}-pc"
                else "";
 
   doCheck = false;
diff --git a/pkgs/tools/misc/mongodb-compass/default.nix b/pkgs/tools/misc/mongodb-compass/default.nix
index f8475ee2e0e0..840d4eacd378 100644
--- a/pkgs/tools/misc/mongodb-compass/default.nix
+++ b/pkgs/tools/misc/mongodb-compass/default.nix
@@ -43,13 +43,13 @@ let
   ] + ":${stdenv.cc.cc.lib}/lib64";
 
   src =
-    if stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchurl {
         url = "https://downloads.mongodb.com/compass/mongodb-compass_${version}_amd64.deb";
         sha256 = "0x23jshnr0rafm5sn2vhq2y2gryg8mksahzyv5fszblgaxay234p";
       }
     else
-      throw "MongoDB compass is not supported on ${stdenv.system}";
+      throw "MongoDB compass is not supported on ${stdenv.hostPlatform.system}";
 
 in stdenv.mkDerivation {
   name = "mongodb-compass-${version}";
diff --git a/pkgs/tools/misc/mprime/default.nix b/pkgs/tools/misc/mprime/default.nix
index 850ed32998b4..e18e9020e1da 100644
--- a/pkgs/tools/misc/mprime/default.nix
+++ b/pkgs/tools/misc/mprime/default.nix
@@ -2,15 +2,15 @@
 
 let
   srcDir =
-    if stdenv.system == "x86_64-linux" then "linux64"
-    else if stdenv.system == "i686-linux" then "linux"
-    else if stdenv.system == "x86_64-darwin" then "macosx64"
+    if stdenv.hostPlatform.system == "x86_64-linux" then "linux64"
+    else if stdenv.hostPlatform.system == "i686-linux" then "linux"
+    else if stdenv.hostPlatform.system == "x86_64-darwin" then "macosx64"
     else throwSystem;
-  throwSystem = throw "Unsupported system: ${stdenv.system}";
+  throwSystem = throw "Unsupported system: ${stdenv.hostPlatform.system}";
   gwnum =
-    if stdenv.system == "x86_64-linux" then "make64"
-    else if stdenv.system == "i686-linux" then "makefile"
-    else if stdenv.system == "x86_64-darwin" then "makemac"
+    if stdenv.hostPlatform.system == "x86_64-linux" then "make64"
+    else if stdenv.hostPlatform.system == "i686-linux" then "makefile"
+    else if stdenv.hostPlatform.system == "x86_64-darwin" then "makemac"
     else throwSystem;
 in
 
diff --git a/pkgs/tools/misc/ocz-ssd-guru/default.nix b/pkgs/tools/misc/ocz-ssd-guru/default.nix
index afe7a81ebac8..9ffb89aca6b1 100644
--- a/pkgs/tools/misc/ocz-ssd-guru/default.nix
+++ b/pkgs/tools/misc/ocz-ssd-guru/default.nix
@@ -1,7 +1,7 @@
 { fetchurl, stdenv, xorg, freetype, fontconfig, libGLU_combined, glibc, makeWrapper }:
 
 let
-  system = if stdenv.system == "x86_64-linux" then "linux64" else "linux32";
+  system = if stdenv.hostPlatform.system == "x86_64-linux" then "linux64" else "linux32";
 in
 stdenv.mkDerivation rec {
   name = "ocz-ssd-guru-${version}";
diff --git a/pkgs/tools/misc/os-prober/default.nix b/pkgs/tools/misc/os-prober/default.nix
index 6211c863bd49..59a60e356b80 100644
--- a/pkgs/tools/misc/os-prober/default.nix
+++ b/pkgs/tools/misc/os-prober/default.nix
@@ -24,7 +24,7 @@ stdenv.mkDerivation rec {
     install -Dt $out/share common.sh
 
     # probes
-    case "${stdenv.system}" in
+    case "${stdenv.hostPlatform.system}" in
         i686*|x86_64*) ARCH=x86;;
         powerpc*) ARCH=powerpc;;
         arm*) ARCH=arm;;
diff --git a/pkgs/tools/misc/s6-portable-utils/default.nix b/pkgs/tools/misc/s6-portable-utils/default.nix
index 014e000eabdb..5f56daf3a48d 100644
--- a/pkgs/tools/misc/s6-portable-utils/default.nix
+++ b/pkgs/tools/misc/s6-portable-utils/default.nix
@@ -29,7 +29,7 @@ stdenv.mkDerivation rec {
   # Explicitly setting target ensures code can be compiled against a skalibs
   # binary built on a different version of darwin.
   # http://www.skarnet.org/cgi-bin/archive.cgi?1:mss:623:heiodchokfjdkonfhdph
-  ++ (stdenv.lib.optional stdenv.isDarwin "--build=${stdenv.system}");
+  ++ (stdenv.lib.optional stdenv.isDarwin "--build=${stdenv.hostPlatform.system}");
 
   postInstall = ''
     mkdir -p $doc/share/doc/s6-portable-utils/
diff --git a/pkgs/tools/misc/staruml/default.nix b/pkgs/tools/misc/staruml/default.nix
index 2a06400b411f..486634452ae9 100644
--- a/pkgs/tools/misc/staruml/default.nix
+++ b/pkgs/tools/misc/staruml/default.nix
@@ -13,7 +13,7 @@ stdenv.mkDerivation rec {
   name = "staruml-${version}";
 
   src =
-    if stdenv.system == "i686-linux" then fetchurl {
+    if stdenv.hostPlatform.system == "i686-linux" then fetchurl {
       url = "http://staruml.io/download/release/v${version}/StarUML-v${version}-32-bit.deb";
       sha256 = "0vb3k9m3l6pmsid4shlk0xdjsriq3gxzm8q7l04didsppg0vvq1n";
     } else fetchurl {
diff --git a/pkgs/tools/networking/airfield/default.nix b/pkgs/tools/networking/airfield/default.nix
index 6f6009c107ba..70005038f99d 100644
--- a/pkgs/tools/networking/airfield/default.nix
+++ b/pkgs/tools/networking/airfield/default.nix
@@ -6,7 +6,7 @@
 let
   nodePackages = import ./node.nix {
     inherit pkgs;
-    system = stdenv.system;
+    system = stdenv.hostPlatform.system;
   };
 
   runtimeEnv = buildEnv {
diff --git a/pkgs/tools/networking/filegive/default.nix b/pkgs/tools/networking/filegive/default.nix
index 6fef6a9e7fa9..a76519b36b57 100644
--- a/pkgs/tools/networking/filegive/default.nix
+++ b/pkgs/tools/networking/filegive/default.nix
@@ -21,7 +21,7 @@ stdenv.mkDerivation rec {
   buildInputs = [ go ];
 
   buildPhase = ''
-    ${stdenv.lib.optionalString (stdenv.system == "armv5tel-linux") "export GOARM=5"}
+    ${stdenv.lib.optionalString (stdenv.hostPlatform.system == "armv5tel-linux") "export GOARM=5"}
 
     mkdir $TMPDIR/go
     export GOPATH=$TMPDIR/go
diff --git a/pkgs/tools/networking/logmein-hamachi/default.nix b/pkgs/tools/networking/logmein-hamachi/default.nix
index 2e045ad8de91..c5c7e18ba6d2 100644
--- a/pkgs/tools/networking/logmein-hamachi/default.nix
+++ b/pkgs/tools/networking/logmein-hamachi/default.nix
@@ -4,13 +4,13 @@ with stdenv.lib;
 
 let
   arch =
-    if stdenv.system == "x86_64-linux" then "x64"
-    else if stdenv.system == "i686-linux" then "x86"
+    if stdenv.hostPlatform.system == "x86_64-linux" then "x64"
+    else if stdenv.hostPlatform.system == "i686-linux" then "x86"
     else throwSystem;
-  throwSystem = throw "Unsupported system: ${stdenv.system}";
+  throwSystem = throw "Unsupported system: ${stdenv.hostPlatform.system}";
   sha256 =
-    if stdenv.system == "x86_64-linux" then "11mxa4kls5xjj3462ycrfvfxb1xkk23p5m9iirvwsi0zdmhpnwm8"
-    else if stdenv.system == "i686-linux" then "03ml9xv19km99f0z7fpr21b1zkxvw7q39kjzd8wpb2pds51wnc62"
+    if stdenv.hostPlatform.system == "x86_64-linux" then "11mxa4kls5xjj3462ycrfvfxb1xkk23p5m9iirvwsi0zdmhpnwm8"
+    else if stdenv.hostPlatform.system == "i686-linux" then "03ml9xv19km99f0z7fpr21b1zkxvw7q39kjzd8wpb2pds51wnc62"
     else throwSystem;
   libraries = stdenv.lib.makeLibraryPath [ stdenv.cc.cc ];
 
diff --git a/pkgs/tools/networking/ngrok-2/default.nix b/pkgs/tools/networking/ngrok-2/default.nix
index 23725fb2d874..fdf9067dfee9 100644
--- a/pkgs/tools/networking/ngrok-2/default.nix
+++ b/pkgs/tools/networking/ngrok-2/default.nix
@@ -15,7 +15,7 @@ stdenv.mkDerivation rec {
   } else if stdenv.isDarwin then fetchurl {
     url = "https://bin.equinox.io/c/4VmDzA7iaHb/ngrok-stable-darwin-386.zip";
     sha256 = "0yfd250b55wcpgqd00rqfaa7a82f35fmybb31q5xwdbgc2i47pbh";
-  } else throw "platform ${stdenv.system} not supported!";
+  } else throw "platform ${stdenv.hostPlatform.system} not supported!";
 
   sourceRoot = ".";
 
diff --git a/pkgs/tools/networking/s6-dns/default.nix b/pkgs/tools/networking/s6-dns/default.nix
index db2071ab17da..29d66e4be2ce 100644
--- a/pkgs/tools/networking/s6-dns/default.nix
+++ b/pkgs/tools/networking/s6-dns/default.nix
@@ -33,7 +33,7 @@ in stdenv.mkDerivation rec {
     "--with-dynlib=${skalibs.lib}/lib"
   ]
   ++ (if stdenv.isDarwin then [ "--disable-shared" ] else [ "--enable-shared" ])
-  ++ (stdenv.lib.optional stdenv.isDarwin "--build=${stdenv.system}");
+  ++ (stdenv.lib.optional stdenv.isDarwin "--build=${stdenv.hostPlatform.system}");
 
   postInstall = ''
     mkdir -p $doc/share/doc/s6-dns/
diff --git a/pkgs/tools/networking/s6-networking/default.nix b/pkgs/tools/networking/s6-networking/default.nix
index 1971bbffa406..f7278d5c6a24 100644
--- a/pkgs/tools/networking/s6-networking/default.nix
+++ b/pkgs/tools/networking/s6-networking/default.nix
@@ -61,7 +61,7 @@ stdenv.mkDerivation rec {
        "--with-include=${lib.getDev sslLibs.${sslSupport}}/include"
        "--with-lib=${lib.getLib sslLibs.${sslSupport}}/lib"
      ])
-  ++ (lib.optional stdenv.isDarwin "--build=${stdenv.system}");
+  ++ (lib.optional stdenv.isDarwin "--build=${stdenv.hostPlatform.system}");
 
   postInstall = ''
     mkdir -p $doc/share/doc/s6-networking/
diff --git a/pkgs/tools/networking/strongswan/default.nix b/pkgs/tools/networking/strongswan/default.nix
index 74405a472f8a..2f19294784ec 100644
--- a/pkgs/tools/networking/strongswan/default.nix
+++ b/pkgs/tools/networking/strongswan/default.nix
@@ -68,7 +68,7 @@ stdenv.mkDerivation rec {
       "--enable-af-alg" "--enable-xauth-pam" "--enable-chapoly"
       "--enable-curl" ]
     ++ optionals stdenv.isx86_64 [ "--enable-aesni" "--enable-rdrand" ]
-    ++ optional (stdenv.system == "i686-linux") "--enable-padlock"
+    ++ optional (stdenv.hostPlatform.system == "i686-linux") "--enable-padlock"
     ++ optionals enableTNC [
          "--disable-gmp" "--disable-aes" "--disable-md5" "--disable-sha1" "--disable-sha2" "--disable-fips-prf"
          "--enable-eap-tnc" "--enable-eap-ttls" "--enable-eap-dynamic" "--enable-tnccs-20"
diff --git a/pkgs/tools/package-management/checkinstall/default.nix b/pkgs/tools/package-management/checkinstall/default.nix
index fea6ccedd34f..df1bf794062f 100644
--- a/pkgs/tools/package-management/checkinstall/default.nix
+++ b/pkgs/tools/package-management/checkinstall/default.nix
@@ -37,7 +37,7 @@ stdenv.mkDerivation {
     ./set-buildroot.patch
   ]
 
-  ++ stdenv.lib.optional (stdenv.system == "x86_64-linux") 
+  ++ stdenv.lib.optional (stdenv.hostPlatform.system == "x86_64-linux") 
     # Force use of old memcpy so that installwatch works on Glibc <
     # 2.14.
     ./use-old-memcpy.patch;
diff --git a/pkgs/tools/package-management/nixui/default.nix b/pkgs/tools/package-management/nixui/default.nix
index 6f46b39e65b1..804bbbdf8d71 100644
--- a/pkgs/tools/package-management/nixui/default.nix
+++ b/pkgs/tools/package-management/nixui/default.nix
@@ -9,7 +9,7 @@ let
   };
   nixui = (import ./nixui.nix {
     inherit pkgs;
-    inherit (stdenv) system;
+    inherit (stdenv.hostPlatform) system;
   })."nixui-git://github.com/matejc/nixui.git#0.2.1";
   script = writeScript "nixui" ''
     #! ${stdenv.shell}
diff --git a/pkgs/tools/security/afl/default.nix b/pkgs/tools/security/afl/default.nix
index c61cbeb32682..3476606049d1 100644
--- a/pkgs/tools/security/afl/default.nix
+++ b/pkgs/tools/security/afl/default.nix
@@ -4,9 +4,9 @@
 
 let
   afl-qemu = callPackage ./qemu.nix {};
-  qemu-exe-name = if stdenv.system == "x86_64-linux" then "qemu-x86_64"
-    else if stdenv.system == "i686-linux" then "qemu-i386"
-    else throw "afl: no support for ${stdenv.system}!";
+  qemu-exe-name = if stdenv.hostPlatform.system == "x86_64-linux" then "qemu-x86_64"
+    else if stdenv.hostPlatform.system == "i686-linux" then "qemu-i386"
+    else throw "afl: no support for ${stdenv.hostPlatform.system}!";
 in
 
 stdenv.mkDerivation rec {
diff --git a/pkgs/tools/security/afl/qemu.nix b/pkgs/tools/security/afl/qemu.nix
index 7637dcf246af..82de6474e598 100644
--- a/pkgs/tools/security/afl/qemu.nix
+++ b/pkgs/tools/security/afl/qemu.nix
@@ -16,9 +16,9 @@ let
   aflTypesFile = writeText "afl-types.h"
     (builtins.readFile ./qemu-patches/afl-types.h);
 
-  cpuTarget = if stdenv.system == "x86_64-linux" then "x86_64-linux-user"
-    else if stdenv.system == "i686-linux" then "i386-linux-user"
-    else throw "afl: no support for ${stdenv.system}!";
+  cpuTarget = if stdenv.hostPlatform.system == "x86_64-linux" then "x86_64-linux-user"
+    else if stdenv.hostPlatform.system == "i686-linux" then "i386-linux-user"
+    else throw "afl: no support for ${stdenv.hostPlatform.system}!";
 in
 stdenv.mkDerivation rec {
   name = "afl-${n}";
@@ -33,7 +33,7 @@ stdenv.mkDerivation rec {
       vde2 texinfo libuuid flex bison lzo snappy autoconf
       libcap_ng gnutls
     ]
-    ++ optionals (hasSuffix "linux" stdenv.system) [ libaio ];
+    ++ optionals (hasSuffix "linux" stdenv.hostPlatform.system) [ libaio ];
 
   enableParallelBuilding = true;
 
diff --git a/pkgs/tools/security/encryptr/default.nix b/pkgs/tools/security/encryptr/default.nix
index 2cf07c63a84a..8d0c78764319 100644
--- a/pkgs/tools/security/encryptr/default.nix
+++ b/pkgs/tools/security/encryptr/default.nix
@@ -5,13 +5,13 @@
 }:
 
 let
-  arch = if stdenv.system == "x86_64-linux" then "amd"
-    else if stdenv.system == "i686-linux" then "i386"
-    else throw "Encryptr for ${stdenv.system} not supported!";
+  arch = if stdenv.hostPlatform.system == "x86_64-linux" then "amd"
+    else if stdenv.hostPlatform.system == "i686-linux" then "i386"
+    else throw "Encryptr for ${stdenv.hostPlatform.system} not supported!";
 
-  sha256 = if stdenv.system == "x86_64-linux" then "1j3g467g7ar86hpnh6q9mf7mh2h4ia94mwhk1283zh739s2g53q2"
-    else if stdenv.system == "i686-linux" then "02j9hg9b1jlv25q1sjfhv8d46mii33f94dj0ccn83z9z18q4y2cm"
-    else throw "Encryptr for ${stdenv.system} not supported!";
+  sha256 = if stdenv.hostPlatform.system == "x86_64-linux" then "1j3g467g7ar86hpnh6q9mf7mh2h4ia94mwhk1283zh739s2g53q2"
+    else if stdenv.hostPlatform.system == "i686-linux" then "02j9hg9b1jlv25q1sjfhv8d46mii33f94dj0ccn83z9z18q4y2cm"
+    else throw "Encryptr for ${stdenv.hostPlatform.system} not supported!";
 
 in stdenv.mkDerivation rec {
   name = "encryptr-${version}";
diff --git a/pkgs/tools/security/enpass/default.nix b/pkgs/tools/security/enpass/default.nix
index b99087e475d2..0f0c4233ca9d 100644
--- a/pkgs/tools/security/enpass/default.nix
+++ b/pkgs/tools/security/enpass/default.nix
@@ -1,8 +1,9 @@
-{stdenv, system, fetchurl, dpkg, openssl, xorg
+{ stdenv, fetchurl, dpkg, openssl, xorg
 , glib, libGLU_combined, libpulseaudio, zlib, dbus, fontconfig, freetype
 , gtk2, pango, atk, cairo, gdk_pixbuf, jasper, xkeyboardconfig
 , makeWrapper , python, pythonPackages, lib
-, libredirect, lsof}:
+, libredirect, lsof
+}:
 
 let
   all_data = builtins.fromJSON (builtins.readFile ./data.json);
@@ -11,7 +12,7 @@ let
     x86_64-linux = "amd64";
   };
 
-  data = all_data.${system_map.${system} or (throw "Unsupported platform")};
+  data = all_data.${system_map.${stdenv.hostPlatform.system} or (throw "Unsupported platform")};
 
   baseUrl = http://repo.sinew.in;
 
diff --git a/pkgs/tools/security/pcsc-scm-scl011/default.nix b/pkgs/tools/security/pcsc-scm-scl011/default.nix
index 1418a4ead580..88ca8a3d1b1a 100644
--- a/pkgs/tools/security/pcsc-scm-scl011/default.nix
+++ b/pkgs/tools/security/pcsc-scm-scl011/default.nix
@@ -1,9 +1,9 @@
 { stdenv, fetchurl, unzip, libusb }:
 
 let
-  arch = if stdenv.system == "i686-linux" then "32"
-  else if stdenv.system == "x86_64-linux" then "64"
-  else throw "Unsupported system: ${stdenv.system}";
+  arch = if stdenv.hostPlatform.system == "i686-linux" then "32"
+  else if stdenv.hostPlatform.system == "x86_64-linux" then "64"
+  else throw "Unsupported system: ${stdenv.hostPlatform.system}";
 in
 stdenv.mkDerivation rec {
   name = "pcsc-scm-scl-${version}";
diff --git a/pkgs/tools/security/sshuttle/default.nix b/pkgs/tools/security/sshuttle/default.nix
index f7878df228f2..c701b9dba73d 100644
--- a/pkgs/tools/security/sshuttle/default.nix
+++ b/pkgs/tools/security/sshuttle/default.nix
@@ -12,7 +12,7 @@ python3Packages.buildPythonApplication rec {
 
   patches = [ ./sudo.patch ];
 
-  nativeBuildInputs = [ makeWrapper python3Packages.setuptools_scm ] ++ stdenv.lib.optional (stdenv.system != "i686-linux") pandoc;
+  nativeBuildInputs = [ makeWrapper python3Packages.setuptools_scm ] ++ stdenv.lib.optional (stdenv.hostPlatform.system != "i686-linux") pandoc;
   buildInputs =
     [ coreutils openssh procps nettools ]
     ++ stdenv.lib.optionals stdenv.isLinux [ iptables ];
diff --git a/pkgs/tools/system/s6-rc/default.nix b/pkgs/tools/system/s6-rc/default.nix
index f6eed5671cea..40c999d80f13 100644
--- a/pkgs/tools/system/s6-rc/default.nix
+++ b/pkgs/tools/system/s6-rc/default.nix
@@ -39,7 +39,7 @@ in stdenv.mkDerivation rec {
     "--with-dynlib=${s6.out}/lib"
   ]
   ++ (if stdenv.isDarwin then [ "--disable-shared" ] else [ "--enable-shared" ])
-  ++ (stdenv.lib.optional stdenv.isDarwin "--build=${stdenv.system}");
+  ++ (stdenv.lib.optional stdenv.isDarwin "--build=${stdenv.hostPlatform.system}");
 
   postInstall = ''
     mkdir -p $doc/share/doc/s6-rc/
diff --git a/pkgs/tools/system/s6/default.nix b/pkgs/tools/system/s6/default.nix
index 035d4280494c..d7ade3cdb290 100644
--- a/pkgs/tools/system/s6/default.nix
+++ b/pkgs/tools/system/s6/default.nix
@@ -40,7 +40,7 @@ in stdenv.mkDerivation rec {
     "--with-dynlib=${execline.lib}/lib"
   ]
   ++ (if stdenv.isDarwin then [ "--disable-shared" ] else [ "--enable-shared" ])
-  ++ (stdenv.lib.optional stdenv.isDarwin "--build=${stdenv.system}");
+  ++ (stdenv.lib.optional stdenv.isDarwin "--build=${stdenv.hostPlatform.system}");
 
   postInstall = ''
     mkdir -p $doc/share/doc/s6/
diff --git a/pkgs/tools/system/storebrowse/default.nix b/pkgs/tools/system/storebrowse/default.nix
index e56919acc5d5..e3b58a50c925 100644
--- a/pkgs/tools/system/storebrowse/default.nix
+++ b/pkgs/tools/system/storebrowse/default.nix
@@ -21,7 +21,7 @@ stdenv.mkDerivation rec {
     mkdir $TMPDIR/go
     export GOPATH=$TMPDIR/go
 
-    ${stdenv.lib.optionalString (stdenv.system == "armv5tel-linux") "export GOARM=5"}
+    ${stdenv.lib.optionalString (stdenv.hostPlatform.system == "armv5tel-linux") "export GOARM=5"}
 
     GOSQLITE=$GOPATH/src/code.google.com/p/gosqlite
     mkdir -p $GOSQLITE
diff --git a/pkgs/tools/text/gawk/default.nix b/pkgs/tools/text/gawk/default.nix
index c0c06813dc94..15d54f4a2a4d 100644
--- a/pkgs/tools/text/gawk/default.nix
+++ b/pkgs/tools/text/gawk/default.nix
@@ -1,6 +1,6 @@
 { stdenv, fetchurl
 # TODO: links -lsigsegv but loses the reference for some reason
-, withSigsegv ? (false && stdenv.system != "x86_64-cygwin"), libsigsegv
+, withSigsegv ? (false && stdenv.hostPlatform.system != "x86_64-cygwin"), libsigsegv
 , interactive ? false, readline
 
 /* Test suite broke on:
diff --git a/pkgs/tools/text/xidel/default.nix b/pkgs/tools/text/xidel/default.nix
index e1a0a5abf965..66dfa1c6b348 100644
--- a/pkgs/tools/text/xidel/default.nix
+++ b/pkgs/tools/text/xidel/default.nix
@@ -11,17 +11,17 @@ stdenv.mkDerivation rec {
   #};
 
   src =
-    if stdenv.system == "x86_64-linux" then
+    if stdenv.hostPlatform.system == "x86_64-linux" then
       fetchurl {
         url = "mirror://sourceforge/videlibri/Xidel/Xidel%20${version}/xidel_${version}-1_amd64.deb";
         sha256 = "0hskc74y7p4j1x33yx0w4fvr610p2yimas8pxhr6bs7mb9b300h7";
       }
-    else if stdenv.system == "i686-linux" then
+    else if stdenv.hostPlatform.system == "i686-linux" then
       fetchurl {
         url = "mirror://sourceforge/videlibri/Xidel/Xidel%20${version}/xidel_${version}-1_i386.deb";
         sha256 = "07yk5sk1p4jm0jmgjwdm2wq8d2wybi1wkn1qq5j5y03z1pdc3fi6";
       }
-    else throw "xidel is not supported on ${stdenv.system}";
+    else throw "xidel is not supported on ${stdenv.hostPlatform.system}";
 
   buildInputs = [ dpkg ];
 
diff --git a/pkgs/tools/typesetting/kindlegen/default.nix b/pkgs/tools/typesetting/kindlegen/default.nix
index 4e9a40239bfe..fc43ed0abe27 100644
--- a/pkgs/tools/typesetting/kindlegen/default.nix
+++ b/pkgs/tools/typesetting/kindlegen/default.nix
@@ -11,7 +11,7 @@ let
     "i686-darwin"   = "0zniyn0s41fxqrajbgwxbcsj5vzf9m7a6yvdz2b11mphr00kpbbs";
     "x86_64-cygwin" = "02slfh1bbpijay4skj85cjiv7z43ha8vm5aa1lwiqjk86qbl1f3h";
     "i686-cygwin"   = "02slfh1bbpijay4skj85cjiv7z43ha8vm5aa1lwiqjk86qbl1f3h";
-  }."${stdenv.system}" or (throw "system #{stdenv.system.} is not supported");
+  }."${stdenv.hostPlatform.system}" or (throw "system #{stdenv.hostPlatform.system.} is not supported");
 
   url = {
     "x86_64-linux"  = "http://kindlegen.s3.amazonaws.com/kindlegen_linux_2.6_i386_v${fileVersion}.tar.gz";
@@ -20,7 +20,7 @@ let
     "i686-darwin"   = "http://kindlegen.s3.amazonaws.com/KindleGen_Mac_i386_v${fileVersion}.zip";
     "x86_64-cygwin" = "http://kindlegen.s3.amazonaws.com/kindlegen_win32_v${fileVersion}.zip";
     "i686-cygwin"   = "http://kindlegen.s3.amazonaws.com/kindlegen_win32_v${fileVersion}.zip";
-  }."${stdenv.system}" or (throw "system #{stdenv.system.} is not supported");
+  }."${stdenv.hostPlatform.system}" or (throw "system #{stdenv.hostPlatform.system.} is not supported");
 
 in stdenv.mkDerivation rec {
   name = "kindlegen-${version}";
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 318b1941e9a0..d6bb0f3cc4e3 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -1744,7 +1744,7 @@ with pkgs;
   chunksync = callPackage ../tools/backup/chunksync { };
 
   cipherscan = callPackage ../tools/security/cipherscan {
-    openssl = if stdenv.system == "x86_64-linux"
+    openssl = if stdenv.hostPlatform.system == "x86_64-linux"
       then openssl-chacha
       else openssl;
   };
@@ -6428,7 +6428,7 @@ with pkgs;
   gcc8Stdenv = overrideCC gccStdenv gcc8;
 
   wrapCCMulti = cc:
-    if system == "x86_64-linux" then let
+    if stdenv.targetPlatform.system == "x86_64-linux" then let
       # Binutils with glibc multi
       bintools = cc.bintools.override {
         libc = glibc_multi;
@@ -6448,16 +6448,16 @@ with pkgs;
       extraBuildCommands = ''
         echo "dontMoveLib64=1" >> $out/nix-support/setup-hook
       '';
-  }) else throw "Multilib ${cc.name} not supported on ‘${system}’";
+  }) else throw "Multilib ${cc.name} not supported for ‘${stdenv.targetPlatform.system}’";
 
   wrapClangMulti = clang:
-    if system == "x86_64-linux" then
+    if stdenv.targetPlatform.system == "x86_64-linux" then
       callPackage ../development/compilers/llvm/multi.nix {
         inherit clang;
         gcc32 = pkgsi686Linux.gcc;
         gcc64 = pkgs.gcc;
       }
-    else throw "Multilib ${clang.cc.name} not supported on '${system}'";
+    else throw "Multilib ${clang.cc.name} not supported for '${stdenv.targetPlatform.system}'";
 
   gcc_multi = wrapCCMulti gcc;
   clang_multi = wrapClangMulti clang;
@@ -11137,7 +11137,7 @@ with pkgs;
   # Default derivation with libGL.so.1 to link into /run/opengl-drivers (if need)
   libGL_driver = libGLDarwinOr mesa_drivers;
 
-  libGLSupported = lib.elem system lib.platforms.mesaPlatforms;
+  libGLSupported = lib.elem stdenv.hostPlatform.system lib.platforms.mesaPlatforms;
 
   libGLDarwin = callPackage ../development/libraries/mesa-darwin {
     inherit (darwin.apple_sdk.frameworks) OpenGL;
@@ -12410,21 +12410,21 @@ with pkgs;
 
   wxGTK28 = callPackage ../development/libraries/wxwidgets/2.8 {
     inherit (gnome2) GConf;
-    withMesa = lib.elem system lib.platforms.mesaPlatforms;
+    withMesa = lib.elem stdenv.hostPlatform.system lib.platforms.mesaPlatforms;
   };
 
   wxGTK29 = callPackage ../development/libraries/wxwidgets/2.9 {
     inherit (gnome2) GConf;
     inherit (darwin.stubs) setfile;
     inherit (darwin.apple_sdk.frameworks) AGL Carbon Cocoa Kernel QuickTime;
-    withMesa = lib.elem system lib.platforms.mesaPlatforms;
+    withMesa = lib.elem stdenv.hostPlatform.system lib.platforms.mesaPlatforms;
   };
 
   wxGTK30 = callPackage ../development/libraries/wxwidgets/3.0 {
     inherit (gnome2) GConf;
     inherit (darwin.stubs) setfile;
     inherit (darwin.apple_sdk.frameworks) AGL Carbon Cocoa Kernel QTKit;
-    withMesa = lib.elem system lib.platforms.mesaPlatforms;
+    withMesa = lib.elem stdenv.hostPlatform.system lib.platforms.mesaPlatforms;
   };
 
   wxGTK31 = callPackage ../development/libraries/wxwidgets/3.1 {};
@@ -17648,7 +17648,7 @@ with pkgs;
     }) murmur_git;
 
   mumble_overlay = callPackage ../applications/networking/mumble/overlay.nix {
-    mumble_i686 = if system == "x86_64-linux"
+    mumble_i686 = if stdenv.hostPlatform.system == "x86_64-linux"
       then pkgsi686Linux.mumble
       else null;
   };
@@ -19049,7 +19049,7 @@ with pkgs;
   };
 
   virtualgl = callPackage ../tools/X11/virtualgl {
-    virtualglLib_i686 = if system == "x86_64-linux"
+    virtualglLib_i686 = if stdenv.hostPlatform.system == "x86_64-linux"
       then pkgsi686Linux.virtualglLib
       else null;
   };
@@ -19062,17 +19062,17 @@ with pkgs;
 
   primus = callPackage ../tools/X11/primus {
     stdenv_i686 = pkgsi686Linux.stdenv;
-    primusLib_i686 = if system == "x86_64-linux"
+    primusLib_i686 = if stdenv.hostPlatform.system == "x86_64-linux"
       then pkgsi686Linux.primusLib
       else null;
   };
 
   bumblebee = callPackage ../tools/X11/bumblebee {
     nvidia_x11 = linuxPackages.nvidia_x11;
-    nvidia_x11_i686 = if system == "x86_64-linux"
+    nvidia_x11_i686 = if stdenv.hostPlatform.system == "x86_64-linux"
       then pkgsi686Linux.linuxPackages.nvidia_x11.override { libsOnly = true; }
       else null;
-    libglvnd_i686 = if system == "x86_64-linux"
+    libglvnd_i686 = if stdenv.hostPlatform.system == "x86_64-linux"
       then pkgsi686Linux.libglvnd
       else null;
   };
@@ -21629,7 +21629,7 @@ with pkgs;
    */
   nixos = configuration:
     (import (self.path + "/nixos/lib/eval-config.nix") {
-      inherit (pkgs) system;
+      inherit (pkgs.stdenv.hostPlatform) system;
       modules = [(
                   { lib, ... }: {
                     config.nixpkgs.pkgs = lib.mkDefault pkgs;
diff --git a/pkgs/top-level/ocaml-packages.nix b/pkgs/top-level/ocaml-packages.nix
index 5787f84335b0..f371e9aa8725 100644
--- a/pkgs/top-level/ocaml-packages.nix
+++ b/pkgs/top-level/ocaml-packages.nix
@@ -1,6 +1,8 @@
-{ lib, callPackage, newScope, pkgs, config, system }:
+{ lib, callPackage, newScope, pkgs, config }:
 
 let
+  inherit (pkgs.stdenv.hostPlatform) system;
+
   mkOcamlPackages = ocaml: overrides:
     let
       packageSet = self:
diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index 96c44cd2a1e3..15ec15732f2d 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -2792,13 +2792,13 @@ in {
     };
   };
 
-  gurobipy = if stdenv.system == "x86_64-darwin"
+  gurobipy = if stdenv.hostPlatform.system == "x86_64-darwin"
   then callPackage ../development/python-modules/gurobipy/darwin.nix {
     inherit (pkgs.darwin) cctools insert_dylib;
   }
-  else if stdenv.system == "x86_64-linux"
+  else if stdenv.hostPlatform.system == "x86_64-linux"
   then callPackage ../development/python-modules/gurobipy/linux.nix {}
-  else throw "gurobipy not yet supported on ${stdenv.system}";
+  else throw "gurobipy not yet supported on ${stdenv.hostPlatform.system}";
 
   hbmqtt = callPackage ../development/python-modules/hbmqtt { };