diff --git a/pkgs/by-name/gr/gravit/package.nix b/pkgs/by-name/gr/gravit/package.nix
index b763b0e74dc5..ea3216dba79a 100644
--- a/pkgs/by-name/gr/gravit/package.nix
+++ b/pkgs/by-name/gr/gravit/package.nix
@@ -64,7 +64,7 @@ stdenv.mkDerivation (finalAttrs: {
 
   enableParallelBuilding = true;
 
-  NIX_CFLAGS_COMPILE = [
+  env.NIX_CFLAGS_COMPILE = toString [
     "-DSDL_INCLUDE_GLU_H"
   ];