diff --git a/pkgs/development/libraries/gtk+/2.x.nix b/pkgs/development/libraries/gtk+/2.x.nix
index 6b889f76ca5..8c6e76726af 100644
--- a/pkgs/development/libraries/gtk+/2.x.nix
+++ b/pkgs/development/libraries/gtk+/2.x.nix
@@ -18,7 +18,7 @@ stdenv.mkDerivation rec {
   enableParallelBuilding = true;
 
   NIX_CFLAGS_COMPILE = "-I${cairo}/include/cairo"
-    + stdenv.lib.optionalString (libintlOrEmpty != null) " -lintl";
+    + stdenv.lib.optionalString (libintlOrEmpty != []) " -lintl";
 
   nativeBuildInputs = [ perl pkgconfig gettext ];