diff --git a/modules/system/boot/stage-1-init.sh b/modules/system/boot/stage-1-init.sh
index 17c9d2b3ee0..7a5ebedd7a8 100644
--- a/modules/system/boot/stage-1-init.sh
+++ b/modules/system/boot/stage-1-init.sh
@@ -127,6 +127,9 @@ fi
 if test -n "$debug1devices"; then fail; fi
 
 
+@postDeviceCommands@
+
+
 # Return true if the machine is on AC power, or if we can't determine
 # whether it's on AC power.
 onACPower() {
@@ -223,6 +226,9 @@ for ((n = 0; n < ${#mountPoints[*]}; n++)); do
     case $device in
         /dev/*)
             ;;
+        //*)
+            # Don't touch SMB/CIFS paths.
+            ;;
         /*)
             device=/mnt-root$device
             ;;
diff --git a/modules/system/boot/stage-1.nix b/modules/system/boot/stage-1.nix
index da8a50f4903..3ff69ac12da 100644
--- a/modules/system/boot/stage-1.nix
+++ b/modules/system/boot/stage-1.nix
@@ -62,12 +62,22 @@ let
       '';
     };
 
+    boot.initrd.postDeviceCommands = mkOption {
+      default = "";
+      merge = pkgs.lib.mergeStringOption;
+      description = ''
+        Shell commands to be executed immediately after stage 1 of the
+        boot has loaded kernel modules and created device nodes in
+        /dev.
+      '';
+    };
+
     boot.initrd.postMountCommands = mkOption {
       default = "";
       merge = pkgs.lib.mergeStringOption;
       description = ''
         Shell commands to be executed immediately after the stage 1
-        filesystems has been mounted.
+        filesystems have been mounted.
       '';
     };
 
@@ -232,7 +242,8 @@ let
     
     inherit (config.boot) isLiveCD resumeDevice;
 
-    inherit (config.boot.initrd) checkJournalingFS postMountCommands;
+    inherit (config.boot.initrd) checkJournalingFS
+      postDeviceCommands postMountCommands;
 
     # !!! copy&pasted from upstart-jobs/filesystems.nix.
     mountPoints =
diff --git a/modules/virtualisation/qemu-vm.nix b/modules/virtualisation/qemu-vm.nix
index eae0541f338..af1911a1ae6 100644
--- a/modules/virtualisation/qemu-vm.nix
+++ b/modules/virtualisation/qemu-vm.nix
@@ -16,25 +16,30 @@
   boot.initrd.extraKernelModules =
     ["cifs" "virtio_net" "virtio_pci" "virtio_blk" "virtio_balloon" "nls_utf8"];
 
+  boot.initrd.postDeviceCommands =
+    ''
+      ipconfig 10.0.2.15:::::eth0:none
+    '';
+
+  # Mount the host filesystem via CIFS, and bind-mount the Nix store
+  # of the host into our own filesystem.
   fileSystems =
     [ { mountPoint = "/";
         device = "/dev/vda";
       }
+      { mountPoint = "/hostfs";
+        device = "//10.0.2.4/qemu";
+        fsType = "cifs";
+        options = "guest,username=nobody";
+        neededForBoot = true;
+      }
+      { mountPoint = "/nix/store";
+        device = "/hostfs/nix/store";
+        options = "bind";
+        neededForBoot = true;
+      }
     ];
 
-  # Mount the host filesystem and bind-mount its Nix store into our
-  # own root FS.
-  boot.initrd.postMountCommands =
-    ''
-      ipconfig 10.0.2.15:::::eth0:none
-      
-      mkdir /hostfs
-      ${pkgs.vmTools.mountCifs}/bin/mount.cifs //10.0.2.4/qemu /hostfs -o guest,username=nobody
-
-      mkdir -p $targetRoot/nix/store
-      mount --bind /hostfs/nix/store $targetRoot/nix/store
-    '';
-
   # Starting DHCP brings down eth0, which kills the connection to the
   # host filesystem and thus deadlocks the system.
   networking.useDHCP = false;