diff --git a/lib/6to5/transformation/transformers/optional-core-aliasing.js b/lib/6to5/transformation/transformers/optional-core-aliasing.js
index 6f97bd2c99..3610ae8f62 100644
--- a/lib/6to5/transformation/transformers/optional-core-aliasing.js
+++ b/lib/6to5/transformation/transformers/optional-core-aliasing.js
@@ -14,8 +14,7 @@ var ALIASABLE_CONSTRUCTORS = [
   "Map",
   "WeakMap",
   "Set",
-  "WeakSet",
-  "Dict",
+  "WeakSet"
 ];
 
 exports.optional = true;