diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index cc4c1305da75..e3de5ccd414f 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -2476,6 +2476,7 @@ let
       xulrunner = firefox40Pkgs.xulrunner;
     };
 
+  xulrunner = firefox40Pkgs.xulrunner;
 
   ### DEVELOPMENT / MISC