diff --git a/pkgs/tools/package-management/nix/unstable.nix b/pkgs/tools/package-management/nix/unstable.nix
index a33e64f55dc..03386da9a57 100644
--- a/pkgs/tools/package-management/nix/unstable.nix
+++ b/pkgs/tools/package-management/nix/unstable.nix
@@ -7,7 +7,7 @@ stdenv.mkDerivation rec {
   name = "nix-0.16pre21576";
 
   src = fetchurl {
-    url = "http://hydra.nixos.org/build/395008/download/4/${name}.bz2";
+    url = "http://hydra.nixos.org/build/395008/download/4/${name}.tar.bz2";
     sha256 = "1axmipk8vp9vwsq5wnhshgb0pcgbhanlxz8z2m3f5vxvixvw3i19";
   };