diff --git a/pkgs/tools/package-management/nix/unstable.nix b/pkgs/tools/package-management/nix/unstable.nix
index c9cf7dc79167..f61b9eb818ae 100644
--- a/pkgs/tools/package-management/nix/unstable.nix
+++ b/pkgs/tools/package-management/nix/unstable.nix
@@ -5,11 +5,11 @@
 }:
 
 stdenv.mkDerivation rec {
-  name = "nix-1.7pre3576_2b6c8ef";
+  name = "nix-1.8pre3636_9d0709e";
 
   src = fetchurl {
-    url = "http://hydra.nixos.org/build/10201398/download/5/${name}.tar.xz";
-    sha256 = "7a735ac859a88a7042b1a7f33f3ab94e9374a0695c68cceb63d4536a79986236";
+    url = "http://hydra.nixos.org/build/11854244/download/5/${name}.tar.xz";
+    sha256 = "13h32d4nbkhvxhj9nyamxf6mfsi7mzvjz1bhyy63088vx468nhmm";
   };
 
   nativeBuildInputs = [ perl pkgconfig ];
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index ffe8e7185b66..b3ba6a64df2f 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -10917,13 +10917,10 @@ let
     stateDir = config.nix.stateDir or "/nix/var";
   };
 
-  nixUnstable = nixStable;
-  /*
   nixUnstable = callPackage ../tools/package-management/nix/unstable.nix {
     storeDir = config.nix.storeDir or "/nix/store";
     stateDir = config.nix.stateDir or "/nix/var";
   };
-  */
 
   nixops = callPackage ../tools/package-management/nixops { };