diff --git a/configuration/rescue-cd.nix b/configuration/rescue-cd.nix
index 05420975d5f..a429304071d 100644
--- a/configuration/rescue-cd.nix
+++ b/configuration/rescue-cd.nix
@@ -3,6 +3,7 @@
     if builtins.pathExists ../relname
     then builtins.readFile ../relname
     else "nixos-${builtins.readFile ../VERSION}"
+, compressImage ? false
 }:
 
 rec {
@@ -304,6 +305,8 @@ rec {
     
     bootable = true;
     bootImage = "boot/grub/stage2_eltorito";
+
+    inherit compressImage;
   };
 
 
diff --git a/helpers/make-iso9660-image.nix b/helpers/make-iso9660-image.nix
index 5e0bca4c630..076820bb5c2 100644
--- a/helpers/make-iso9660-image.nix
+++ b/helpers/make-iso9660-image.nix
@@ -25,6 +25,9 @@
   # The path (in the ISO file system) of the boot image.
 , bootImage ? ""
 
+, # Whether to compress the resulting ISO image with bzip2.
+  compressImage ? false
+
 }:
 
 assert bootable -> bootImage != "";
@@ -33,7 +36,7 @@ stdenv.mkDerivation {
   name = "iso9660-image";
   builder = ./make-iso9660-image.sh;
   buildInputs = [perl cdrkit];
-  inherit isoName bootable bootImage;
+  inherit isoName bootable bootImage compressImage;
 
   # !!! should use XML.
   sources = map (x: x.source) contents;
diff --git a/helpers/make-iso9660-image.sh b/helpers/make-iso9660-image.sh
index 5ad8cb475de..9330002f0b4 100644
--- a/helpers/make-iso9660-image.sh
+++ b/helpers/make-iso9660-image.sh
@@ -59,10 +59,15 @@ done
 
 cat pathlist | sed -e 's/=\(.*\)=\(.*\)=/\\=\1=\2\\=/' | tee pathlist.safer
 
-# !!! -f is a quick hack.
+
 ensureDir $out/iso
-genisoimage -r -J -o $out/iso/$isoName $bootFlags \
-    -hide-rr-moved -graft-points -path-list pathlist.safer
+genCommand="genisoimage -r -J $bootFlags -hide-rr-moved -graft-points -path-list pathlist.safer"
+if test -z "$compressImage"; then
+    $genCommand -o $out/iso/$isoName
+else
+    $genCommand | bzip2 > $out/iso/$isoName.bz2
+fi
+    
 
 ensureDir $out/nix-support
 echo $system > $out/nix-support/system