diff --git a/nixos/lib/test-driver/Machine.pm b/nixos/lib/test-driver/Machine.pm
index 7e269b43e70f..b18f48464cee 100644
--- a/nixos/lib/test-driver/Machine.pm
+++ b/nixos/lib/test-driver/Machine.pm
@@ -33,9 +33,20 @@ sub new {
         $startCommand =
             "qemu-kvm -m 384 " .
             "-net nic,model=virtio \$QEMU_OPTS ";
-        my $iface = $args->{hdaInterface} || "virtio";
-        $startCommand .= "-drive file=" . Cwd::abs_path($args->{hda}) . ",if=$iface,werror=report "
-            if defined $args->{hda};
+
+        if (defined $args->{hda}) {
+            if ($args->{hdaInterface} eq "scsi") {
+                $startCommand .= "-drive id=hda,file="
+                               . Cwd::abs_path($args->{hda})
+                               . ",werror=report,if=none "
+                               . "-device scsi-hd,drive=hda ";
+            } else {
+                $startCommand .= "-drive file=" . Cwd::abs_path($args->{hda})
+                               . ",if=" . $args->{hdaInterface}
+                               . ",werror=report ";
+            }
+        }
+
         $startCommand .= "-cdrom $args->{cdrom} "
             if defined $args->{cdrom};
         $startCommand .= "-device piix3-usb-uhci -drive id=usbdisk,file=$args->{usb},if=none,readonly -device usb-storage,drive=usbdisk "
diff --git a/nixos/modules/virtualisation/qemu-vm.nix b/nixos/modules/virtualisation/qemu-vm.nix
index 3d4bd315f812..66ff43c8547d 100644
--- a/nixos/modules/virtualisation/qemu-vm.nix
+++ b/nixos/modules/virtualisation/qemu-vm.nix
@@ -27,6 +27,21 @@ let
   kernelConsole = if cfg.graphics then "" else "console=${qemuSerialDevice}";
   ttys = [ "tty1" "tty2" "tty3" "tty4" "tty5" "tty6" ];
 
+  # XXX: This is very ugly and in the future we really should use attribute
+  # sets to build ALL of the QEMU flags instead of this mixed mess of Nix
+  # expressions and shell script stuff.
+  mkDiskIfaceDriveFlag = idx: driveArgs: let
+    inherit (cfg.qemu) diskInterface;
+    # The drive identifier created by incrementing the index by one using the
+    # shell.
+    drvId = "drive$((${idx} + 1))";
+    # NOTE: DO NOT shell escape, because this may contain shell variables.
+    commonArgs = "index=${idx},id=${drvId},${driveArgs}";
+    isSCSI = diskInterface == "scsi";
+    devArgs = "${diskInterface}-hd,drive=${drvId}";
+    args = "-drive ${commonArgs},if=none -device lsi53c895a -device ${devArgs}";
+  in if isSCSI then args else "-drive ${commonArgs},if=${diskInterface}";
+
   # Shell script to start the VM.
   startVM =
     ''
@@ -68,7 +83,7 @@ let
         if ! test -e "empty$idx.qcow2"; then
             ${qemu}/bin/qemu-img create -f qcow2 "empty$idx.qcow2" "${toString size}M"
         fi
-        extraDisks="$extraDisks -drive index=$idx,file=$(pwd)/empty$idx.qcow2,if=${cfg.qemu.diskInterface},werror=report"
+        extraDisks="$extraDisks ${mkDiskIfaceDriveFlag "$idx" "file=$(pwd)/empty$idx.qcow2,werror=report"}"
         idx=$((idx + 1))
       '')}
 
@@ -83,14 +98,14 @@ let
           -virtfs local,path=$TMPDIR/xchg,security_model=none,mount_tag=xchg \
           -virtfs local,path=''${SHARED_DIR:-$TMPDIR/xchg},security_model=none,mount_tag=shared \
           ${if cfg.useBootLoader then ''
-            -drive index=0,id=drive1,file=$NIX_DISK_IMAGE,if=${cfg.qemu.diskInterface},cache=writeback,werror=report \
-            -drive index=1,id=drive2,file=$TMPDIR/disk.img,media=disk \
+            ${mkDiskIfaceDriveFlag "0" "file=$NIX_DISK_IMAGE,cache=writeback,werror=report"} \
+            ${mkDiskIfaceDriveFlag "1" "file=$TMPDIR/disk.img,media=disk"} \
             ${if cfg.useEFIBoot then ''
               -pflash $TMPDIR/bios.bin \
             '' else ''
             ''}
           '' else ''
-            -drive index=0,id=drive1,file=$NIX_DISK_IMAGE,if=${cfg.qemu.diskInterface},cache=writeback,werror=report \
+            ${mkDiskIfaceDriveFlag "0" "file=$NIX_DISK_IMAGE,cache=writeback,werror=report"} \
             -kernel ${config.system.build.toplevel}/kernel \
             -initrd ${config.system.build.toplevel}/initrd \
             -append "$(cat ${config.system.build.toplevel}/kernel-params) init=${config.system.build.toplevel}/init regInfo=${regInfo}/registration ${kernelConsole} $QEMU_KERNEL_PARAMS" \
@@ -338,11 +353,8 @@ in
         mkOption {
           default = "virtio";
           example = "scsi";
-          type = types.str;
-          description = ''
-            The interface used for the virtual hard disks
-            (<literal>virtio</literal> or <literal>scsi</literal>).
-          '';
+          type = types.enum [ "virtio" "scsi" "ide" ];
+          description = "The interface used for the virtual hard disks.";
         };
     };