diff --git a/pkgs/development/tools/packcc/default.nix b/pkgs/development/tools/packcc/default.nix
index b16b0491c9b6..4f618665573c 100644
--- a/pkgs/development/tools/packcc/default.nix
+++ b/pkgs/development/tools/packcc/default.nix
@@ -35,6 +35,8 @@ stdenv.mkDerivation rec {
 
     # Disable a failing test.
     rm -rf ../../tests/style.d
+  '' + lib.optionalString stdenv.cc.isClang ''
+    export NIX_CFLAGS_COMPILE+=' -Wno-error=strict-prototypes -Wno-error=int-conversion'
   '';
 
   installPhase = ''