diff --git a/pkgs/build-support/release/source-tarball.nix b/pkgs/build-support/release/source-tarball.nix
index 376cd0e1d15..5e178544644 100644
--- a/pkgs/build-support/release/source-tarball.nix
+++ b/pkgs/build-support/release/source-tarball.nix
@@ -94,6 +94,7 @@ stdenv.mkDerivation (
       touch now
       touch -d "1970-01-01 00:00:00 UTC" then
       find $sourceRoot ! -newer then -print0 | xargs -0r touch --reference now
+      rm now then
       eval "$nextPostUnpack"
     '';