diff --git a/pkgs/by-name/go/goupile/package.nix b/pkgs/by-name/go/goupile/package.nix
index a99a5f88539e..91bf214ed0ab 100644
--- a/pkgs/by-name/go/goupile/package.nix
+++ b/pkgs/by-name/go/goupile/package.nix
@@ -43,7 +43,9 @@ stdenv'.mkDerivation (finalAttrs: {
   ];
 
   # pipe2() is only exposed with _GNU_SOURCE
-  NIX_CFLAGS_COMPILE = [ "-D_GNU_SOURCE" ];
+  env.NIX_CFLAGS_COMPILE = toString [
+    "-D_GNU_SOURCE"
+  ];
 
   buildPhase = ''
     runHook preBuild