diff --git a/externs/polymer-externs.js b/externs/polymer-externs.js
index 0a86620b69..53bcf01323 100644
--- a/externs/polymer-externs.js
+++ b/externs/polymer-externs.js
@@ -109,4 +109,4 @@ Polymer.version;
  * @extends {HTMLElement}
  * @implements {Polymer_LegacyElementMixin}
  */
-var PolymerElement = Polymer.LegacyElementMixin();
+var PolymerElement = function() {};