diff --git a/lib/6to5/templates/extends.js b/lib/6to5/templates/extends.js
index bc950dfd9a..1e8f6b5e8f 100644
--- a/lib/6to5/templates/extends.js
+++ b/lib/6to5/templates/extends.js
@@ -1,5 +1,5 @@
 (function (child, parent) {
-  child.prototype = Object.create(parent.prototype, {
+  child.prototype = Object.create(parent && parent.prototype, {
     constructor: {
       value: child,
       enumerable: false,
@@ -7,5 +7,5 @@
       configurable: true
     }
   });
-  child.__proto__ = parent;
+  if (parent) child.__proto__ = parent;
 })