diff --git a/pkgs/applications/version-management/mercurial/default.nix b/pkgs/applications/version-management/mercurial/default.nix
index 253907ab4bd..f65a34ec5c4 100644
--- a/pkgs/applications/version-management/mercurial/default.nix
+++ b/pkgs/applications/version-management/mercurial/default.nix
@@ -1,10 +1,10 @@
-{stdenv, fetchurl, python, makeWrapper}:
+args: with args;
 
 stdenv.mkDerivation {
-  name = "mercurial-0.9.4";
+  name = "mercurial-0.9.5";
   src = fetchurl {
-    url = http://www.selenic.com/mercurial/release/mercurial-0.9.4.tar.gz;
-    sha256 = "26996df67d508e129d2f0a264e25072764e5c2d21606e1658d77c8984e6ed64a";
+    url = http://www.selenic.com/mercurial/release/mercurial-0.9.5.tar.gz;
+    sha256 = "1n34yl4z7nc3vmsgpkmqc94hsmy846ny86xgpgv3m371ljm2pq6g";
   };
 
   inherit makeWrapper;
@@ -16,7 +16,7 @@ stdenv.mkDerivation {
     "for i in $(cd $out/bin && ls); do"
     "   mv $out/bin/$i $out/bin/.orig-$i;"
     "   makeWrapper $out/bin/.orig-$i $out/bin/$i"
-    "       --set PYTHONPATH \"$(toPythonPath $out):$PYTHONPATH\";"
+    "       --set PYTHONPATH \"$(toPythonPath $out):$PYTHONPATH:\$PYTHONPATH\";"
     "done"
   ];