diff --git a/pkgs/top-level/make-tarball.nix b/pkgs/top-level/make-tarball.nix
index 16940761e6dc..ccd7b89fc12d 100644
--- a/pkgs/top-level/make-tarball.nix
+++ b/pkgs/top-level/make-tarball.nix
@@ -43,8 +43,10 @@ releaseTools.sourceTarball rec {
     echo 'abort "Illegal use of <nixpkgs> in Nixpkgs."' > $TMPDIR/barf.nix
 
     # Make sure that Nixpkgs does not use <nixpkgs>
-    if (find pkgs -type f -name '*.nix' -print | xargs grep '<nixpkgs\/'); then
+    badFiles=$(find pkgs -type f -name '*.nix' -print | xargs grep -l '^[^#]*<nixpkgs\/' || true)
+    if [[ -n $badFiles ]]; then
         echo "Nixpkgs is not allowed to use <nixpkgs> to refer to itself."
+        echo "The offending files: $badFiles"
         exit 1
     fi