diff --git a/pkgs/development/libraries/buddy/default.nix b/pkgs/development/libraries/buddy/default.nix
index 47b61fe03510..eb9d146291d9 100644
--- a/pkgs/development/libraries/buddy/default.nix
+++ b/pkgs/development/libraries/buddy/default.nix
@@ -12,6 +12,7 @@ stdenv.mkDerivation rec {
   buildInputs = [ bison ];
   patches = [ ./gcc-4.3.3-fixes.patch ];
   configureFlags = [ "CFLAGS=-O3" "CXXFLAGS=-O3" ];
+  env.NIX_CFLAGS_COMPILE = lib.optionalString stdenv.cc.isClang "-Wno-error=register";
   NIX_LDFLAGS = "-lm";
   doCheck = true;