diff --git a/pkgs/development/interpreters/python-new/2.5/default.nix b/pkgs/development/interpreters/python-new/2.5/default.nix
index 76a9317dfae..aa3934160d5 100644
--- a/pkgs/development/interpreters/python-new/2.5/default.nix
+++ b/pkgs/development/interpreters/python-new/2.5/default.nix
@@ -200,8 +200,8 @@ in
         unset installPhase
         export G2CONF="--enable-gconf" # hack, should be specified somewhere else
         for srcs in $pygobjectSrc $pygtkSrc $pySrcs; do
-          cd $TMP; mkdir "$(basename $srcs)"; cd "$(basename $srcs)"; unpackPhase
-          cd $sourceRoot
+          cd $TMP; mkdir "$(basename $srcs)"; cd "$(basename $srcs)"; unpackFile $srcs
+          cd *
           configurePhase; buildPhase; installPhase
             addToEnv $out # pygtk has to know about pygobject
             PATH=$out/bin:$PATH # gnome-python nees pygtk-codegen