diff --git a/pkgs/development/compilers/jdk/builder.sh b/pkgs/development/compilers/jdk/builder.sh
old mode 100755
new mode 100644
index ae3ae055b839..cc70c09b3c85
--- a/pkgs/development/compilers/jdk/builder.sh
+++ b/pkgs/development/compilers/jdk/builder.sh
@@ -1,29 +1,38 @@
-#!/bin/sh
+source $stdenv/setup
 
-. $stdenv/setup || exit 1
 src=$filename.bin
 
-cp $pathname $src || exit 1
+if ! test -e "$pathname"; then
+    echo ""
+    echo "SORRY!"
+    echo "You should download \`$(basename $pathname)' from Sun and place it in $(dirname $pathname)."
+    echo "Blame Sun, not us."
+    echo ""
+    exit 1
+fi
 
-actual=$(md5sum -b $src | cut -c1-32)
+actual=$(md5sum -b $pathname | cut -c1-32)
 if test "$actual" != "$md5"; then
     echo "hash is $actual, expected $md5"
     exit 1
 fi
 
-chmod u+x $src || exit 1
+unzip $pathname || true
 
-alias more=cat
+ensureDir $out
+mv $dirname/* $out/
 
-yes yes | ./$src || exit 1
-
-mkdir $out || exit 1
-mv $dirname/* $out/ || exit 1
-
-# remove crap in the root directory
+# Remove crap in the root directory.
 for file in $out/*
 do
   if test -f $file ; then
     rm $file
   fi
 done
+
+# Unpack .pack files.
+for i in $(find $out -name "*.pack"); do
+    echo "unpacking $i..."
+    $out/bin/unpack200 "$i" "$(dirname $i)/$(basename $i .pack).jar"
+    rm "$i"
+done
diff --git a/pkgs/development/compilers/jdk/default.nix b/pkgs/development/compilers/jdk/default.nix
index ccfd88bb92ae..060d270fb081 100644
--- a/pkgs/development/compilers/jdk/default.nix
+++ b/pkgs/development/compilers/jdk/default.nix
@@ -1,9 +1,9 @@
-{stdenv, fetchurl}: 
+{stdenv, fetchurl, unzip}:
 
 if stdenv.system == "i686-linux"
   then
     (import ./jdk5-sun-linux.nix) {
-      inherit stdenv fetchurl;
+      inherit stdenv fetchurl unzip;
     }
   else
     false
diff --git a/pkgs/development/compilers/jdk/jdk5-sun-linux.nix b/pkgs/development/compilers/jdk/jdk5-sun-linux.nix
index 81ed02232843..3160ad24bbcf 100644
--- a/pkgs/development/compilers/jdk/jdk5-sun-linux.nix
+++ b/pkgs/development/compilers/jdk/jdk5-sun-linux.nix
@@ -8,17 +8,16 @@
  *
  * @author Martin Bravenboer <martin@cs.uu.nl>
  */
-{stdenv, fetchurl}: 
+{stdenv, fetchurl, unzip}:
 
 assert stdenv.system == "i686-linux";
 
-derivation {
+stdenv.mkDerivation {
   name = "jdk-1.5.0";
+  builder = ./builder.sh;
   filename = "jdk-1_5_0_05";
   dirname = "jdk1.5.0_05";
-  system = stdenv.system;
-  builder = ./builder.sh;
   pathname = "/tmp/jdk-1_5_0_05-linux-i586.bin";
   md5 = "2f83bf2a38fff1f8ac51b02ec7391ca3";
-  stdenv = stdenv;
+  buildInputs = [unzip];
 }
diff --git a/pkgs/system/all-packages-generic.nix b/pkgs/system/all-packages-generic.nix
index 392741ea95a6..be95cfb6fdca 100644
--- a/pkgs/system/all-packages-generic.nix
+++ b/pkgs/system/all-packages-generic.nix
@@ -506,7 +506,7 @@ rec {
       "/System/Library/Frameworks/JavaVM.framework/Versions/1.5.0/Home"
     else
       (import ../development/compilers/jdk) {
-        inherit fetchurl stdenv;
+        inherit fetchurl stdenv unzip;
       };
 
   j2sdk14x = (import ../development/compilers/jdk/default-1.4.nix) {