diff --git a/pkgs/build-support/release/source-tarball.nix b/pkgs/build-support/release/source-tarball.nix
index 45a871567482..85d0b29f5b70 100644
--- a/pkgs/build-support/release/source-tarball.nix
+++ b/pkgs/build-support/release/source-tarball.nix
@@ -90,7 +90,7 @@ stdenv.mkDerivation (
 
     buildInputs = buildInputs ++ bootstrapBuildInputs;
     
-    postHook = ''
+    preUnpack = ''
       mkdir -p $out/nix-support
     '';