diff --git a/pkgs/development/web/kore/default.nix b/pkgs/development/web/kore/default.nix
index 3da932b6b17..b0dc2ba041a 100644
--- a/pkgs/development/web/kore/default.nix
+++ b/pkgs/development/web/kore/default.nix
@@ -20,8 +20,9 @@ stdenv.mkDerivation rec {
 
   makeFlags = [ "PREFIX=$(out)" ];
 
-  # added to fix build w/gcc7
-  NIX_CFLAGS_COMPILE = stdenv.lib.optionals stdenv.isLinux [ "-Wno-error=pointer-compare" ];
+  # added to fix build w/gcc7 and clang5
+  NIX_CFLAGS_COMPILE = stdenv.lib.optionalString stdenv.cc.isGNU "-Wno-error=pointer-compare"
+    + stdenv.lib.optionalString stdenv.cc.isClang " -Wno-error=unknown-warning-option";
 
   enableParallelBuilding = true;