diff --git a/boot/make-initrd.nix b/boot/make-initrd.nix
index b737b2f9779..3e5133be08b 100644
--- a/boot/make-initrd.nix
+++ b/boot/make-initrd.nix
@@ -12,12 +12,12 @@
 # `contents = {object = ...; symlink = /init;}' is a typical
 # argument.
 
-{stdenv, cpio, contents}:
+{stdenv, perl, cpio, contents}:
 
 stdenv.mkDerivation {
   name = "initrd";
   builder = ./make-initrd.sh;
-  buildInputs = [cpio];
+  buildInputs = [perl cpio];
 
   # !!! should use XML.
   objects = map (x: x.object) contents;
@@ -27,5 +27,5 @@ stdenv.mkDerivation {
   # For obtaining the closure of `contents'.
   exportReferencesGraph =
     map (x: [("closure-" + baseNameOf x.symlink) x.object]) contents;
-  pathsFromGraph = ../helpers/paths-from-graph.sh;
+  pathsFromGraph = ../helpers/paths-from-graph.pl;
 }
diff --git a/boot/make-initrd.sh b/boot/make-initrd.sh
index 45ee036e4e8..d930e51a03f 100644
--- a/boot/make-initrd.sh
+++ b/boot/make-initrd.sh
@@ -20,23 +20,20 @@ for ((n = 0; n < ${#objects[*]}; n++)); do
     suffix=${suffices[$n]}
     if test "$suffix" = none; then suffix=; fi
 
-    # Get the paths in the closure of `object'.
-    closure=closure-$(basename $symlink)
-    if ! test -e $closure; then
-        echo 'Your Nix installation is too old! Upgrade to nix-0.11pre7038 or newer.'
-        exit 1
-    fi
-    storePaths=$($SHELL $pathsFromGraph $closure)
-
-    # Paths in cpio archives *must* be relative, otherwise the kernel
-    # won't unpack 'em.
-    (cd root && cp -prd --parents $storePaths .)
-
     mkdir -p $(dirname root/$symlink)
     ln -s $object$suffix root/$symlink
 done
 
 
+# Get the paths in the closure of `object'.
+storePaths=$(perl $pathsFromGraph closure-*)
+
+
+# Paths in cpio archives *must* be relative, otherwise the kernel
+# won't unpack 'em.
+(cd root && cp -prd --parents $storePaths .)
+
+
 # Put the closure in a gzipped cpio archive.
 ensureDir $out
 (cd root && find * -print0 | cpio -ov -H newc --null | gzip -9 > $out/initrd)
diff --git a/helpers/paths-from-graph.sh b/helpers/paths-from-graph.sh
deleted file mode 100644
index 4a134cb3165..00000000000
--- a/helpers/paths-from-graph.sh
+++ /dev/null
@@ -1,10 +0,0 @@
-graph="$1"
-
-while read storePath; do
-    echo $storePath
-    read deriver
-    read count
-    for ((i = 0; i < $count; i++)); do
-        read ref
-    done
-done < $graph
diff --git a/system/system.nix b/system/system.nix
index b63e48ce201..4f272d8d7a5 100644
--- a/system/system.nix
+++ b/system/system.nix
@@ -86,7 +86,7 @@ rec {
   # The closure of the init script of boot stage 1 is what we put in
   # the initial RAM disk.
   initialRamdisk = import ../boot/make-initrd.nix {
-    inherit (pkgs) stdenv cpio;
+    inherit (pkgs) perl stdenv cpio;
     contents = [
       { object = bootStage1;
         symlink = "/init";