diff --git a/lib/6to5/transformation/transformers/es6/parameters.default.js b/lib/6to5/transformation/transformers/es6/parameters.default.js
index c529f5a36e..00f2d47f3f 100644
--- a/lib/6to5/transformation/transformers/es6/parameters.default.js
+++ b/lib/6to5/transformation/transformers/es6/parameters.default.js
@@ -13,7 +13,7 @@ var hasDefaults = function (node) {
 
 var iifeVisitor = {
   enter: function (node, parent, scope, context, state) {
-    if (t.isReferencedIdentifier(node, parent) && scope.hasOwn(node.name)) {
+    if (t.isReferencedIdentifier(node, parent) && state.scope.hasOwn(node.name)) {
       state.iife = true;
       context.stop();
     }