diff --git a/pkgs/development/compilers/ats2/default.nix b/pkgs/development/compilers/ats2/default.nix
index b475eab689c5..339d9e6b7e31 100644
--- a/pkgs/development/compilers/ats2/default.nix
+++ b/pkgs/development/compilers/ats2/default.nix
@@ -52,6 +52,8 @@ stdenv.mkDerivation rec {
     "CCOMP=${stdenv.cc.targetPrefix}cc"
   ];
 
+  env.NIX_CFLAGS_COMPILE = lib.optionalString stdenv.cc.isClang "-Wno-error=implicit-function-declaration";
+
   setupHook =
     let
       hookFiles = [ ./setup-hook.sh ] ++ lib.optional withContrib ./setup-contrib-hook.sh;