diff --git a/boot/boot-stage-1-init.sh b/boot/boot-stage-1-init.sh
index 02de35e0cee..3bde517a937 100644
--- a/boot/boot-stage-1-init.sh
+++ b/boot/boot-stage-1-init.sh
@@ -219,7 +219,7 @@ if test -n "@isLiveCD@"; then
     mkdir /mnt/tmpfs
     mount -n -t tmpfs -o "mode=755" none /mnt/tmpfs
     mkdir /mnt/union
-    mount -t unionfs -o dirs=/mnt/tmpfs=rw:$targetRoot=ro none /mnt/union
+    mount -t aufs -o dirs=/mnt/tmpfs=rw:$targetRoot=ro none /mnt/union
     targetRoot=/mnt/union
 fi
 
diff --git a/configuration/rescue-cd.nix b/configuration/rescue-cd.nix
index 435da04db16..2edfe78d9e9 100644
--- a/configuration/rescue-cd.nix
+++ b/configuration/rescue-cd.nix
@@ -15,9 +15,10 @@ rec {
       # The label used to identify the installation CD.
       rootLabel = "NIXOS";
       extraTTYs = [7 8]; # manual, rogue
+      extraModulePackages = [pkgs.aufs];
       initrd = {
         extraKernelModules = [
-          "unionfs" # needed for live-CD operation
+          "aufs" # needed for live-CD operation
         ];
       };
     };
diff --git a/system/options.nix b/system/options.nix
index bf7c38d4dc8..a50ab43929f 100644
--- a/system/options.nix
+++ b/system/options.nix
@@ -123,6 +123,14 @@
       ";
     };
 
+    extraModulePackages = mkOption {
+      default = [];
+      example = [pkgs.aufs pkgs.nvidiaDriver];
+      description = ''
+        A list of additional packages supplying kernel modules.
+      '';
+    };
+
     kernelModules = mkOption {
       default = [];
       description = "
diff --git a/system/system.nix b/system/system.nix
index 732ae7b8aa9..4bc22890cb1 100644
--- a/system/system.nix
+++ b/system/system.nix
@@ -43,7 +43,8 @@ rec {
   # Determine the set of modules that we need to mount the root FS.
   modulesClosure = import ../helpers/modules-closure.nix {
     inherit (pkgs) stdenv module_init_tools;
-    inherit kernel rootModules;
+    inherit rootModules;
+    kernel = modulesTree;
   };
 
 
@@ -148,9 +149,10 @@ rec {
   # directory.
   modulesTree = pkgs.module_aggregation (
     [kernel]
-	++ pkgs.lib.optional config.networking.enableIntel3945ABGFirmware pkgs.iwlwifi
+    ++ pkgs.lib.optional config.networking.enableIntel3945ABGFirmware pkgs.iwlwifi
     # !!! this should be declared by the xserver Upstart job.
     ++ pkgs.lib.optional (config.services.xserver.enable && config.services.xserver.videoDriver == "nvidia") pkgs.nvidiaDrivers
+    ++ config.boot.extraModulePackages
   );