diff --git a/externs/closure-types.js b/externs/closure-types.js
index a140d68e39..478727b505 100644
--- a/externs/closure-types.js
+++ b/externs/closure-types.js
@@ -877,6 +877,10 @@ Polymer_ElementMixin.createProperties = function(props){};
 */
 Polymer_ElementMixin._finalizeClass = function(){};
 /**
+* @return {undefined}
+*/
+Polymer_ElementMixin._prepareTemplate = function(){};
+/**
 * @param {Object} observers Array of observer descriptors for
   this class
 * @param {Object} dynamicFns Object containing keys for any properties
@@ -1299,10 +1303,6 @@ Polymer_LegacyElementMixin.prototype._error = function(args){};
 */
 Polymer_LegacyElementMixin.prototype._logf = function(methodName, args){};
 /**
-* @return {undefined}
-*/
-Polymer_LegacyElementMixin._finalizeClass = function(){};
-/**
 * @interface
 */
 function Polymer_MutableData(){}
diff --git a/types/lib/legacy/legacy-element-mixin.d.ts b/types/lib/legacy/legacy-element-mixin.d.ts
index 40c4be507f..6f4d187381 100644
--- a/types/lib/legacy/legacy-element-mixin.d.ts
+++ b/types/lib/legacy/legacy-element-mixin.d.ts
@@ -30,7 +30,6 @@ declare namespace Polymer {
 
   interface LegacyElementMixinConstructor {
     new(...args: any[]): LegacyElementMixin;
-    _finalizeClass(): void;
   }
 
   interface LegacyElementMixin extends Polymer.ElementMixin, Polymer.PropertyEffects, Polymer.TemplateStamp, Polymer.PropertyAccessors, Polymer.PropertiesChanged, Polymer.PropertiesMixin, Polymer.GestureEventListeners {
diff --git a/types/lib/mixins/element-mixin.d.ts b/types/lib/mixins/element-mixin.d.ts
index c0d43eb01d..8a20237204 100644
--- a/types/lib/mixins/element-mixin.d.ts
+++ b/types/lib/mixins/element-mixin.d.ts
@@ -100,6 +100,7 @@ declare namespace Polymer {
      * find the template.
      */
     _finalizeClass(): void;
+    _prepareTemplate(): void;
 
     /**
      * Creates observers for the given `observers` array.