diff --git a/pkgs/development/tools/misc/pkg-config/default.nix b/pkgs/development/tools/misc/pkg-config/default.nix
index ceca1cf590c0..2cecb25eeeec 100644
--- a/pkgs/development/tools/misc/pkg-config/default.nix
+++ b/pkgs/development/tools/misc/pkg-config/default.nix
@@ -18,7 +18,7 @@ stdenv.mkDerivation rec {
     ++ optional stdenv.isCygwin ./2.36.3-not-win32.patch;
 
   # These three tests fail due to a (desired) behavior change from our ./requires-private.patch
-  postPatch = ''
+  postPatch = if vanilla then null else ''
     rm -f check/check-requires-private check/check-gtk check/missing
   '';