diff --git a/pkgs/by-name/ka/kakasi/package.nix b/pkgs/by-name/ka/kakasi/package.nix
index 9d6d8d0b3244..f68d277afc56 100644
--- a/pkgs/by-name/ka/kakasi/package.nix
+++ b/pkgs/by-name/ka/kakasi/package.nix
@@ -27,9 +27,7 @@ stdenv.mkDerivation (finalAttrs: {
   nativeBuildInputs = [ autoreconfHook ];
   buildInputs = lib.optionals stdenv.hostPlatform.isDarwin [ libiconv ];
 
-  env = lib.optionalAttrs (!stdenv.cc.isClang) {
-    NIX_CFLAGS_COMPILE = "-std=gnu17";
-  };
+  configureFlags = [ "CFLAGS=-std=gnu17" ];
 
   postPatch = ''
     for a in tests/kakasi-* ; do