diff --git a/lib/utils/templatize.html b/lib/utils/templatize.html
index 42b1b2b30e..d4cdbcdc8b 100644
--- a/lib/utils/templatize.html
+++ b/lib/utils/templatize.html
@@ -459,7 +459,7 @@
        *
        * @memberof Polymer.Templatize
        * @param {!HTMLTemplateElement} template Template to templatize
-       * @param {!Polymer_PropertyEffects} owner Owner of the template instances;
+       * @param {Polymer_PropertyEffects=} owner Owner of the template instances;
        *   any optional callbacks will be bound to this owner.
        * @param {Object=} options Options dictionary (see summary for details)
        * @return {function(new:TemplateInstanceBase)} Generated class bound to the template
diff --git a/types/lib/utils/templatize.d.ts b/types/lib/utils/templatize.d.ts
index 882d33c53a..01a2115924 100644
--- a/types/lib/utils/templatize.d.ts
+++ b/types/lib/utils/templatize.d.ts
@@ -141,7 +141,7 @@ declare namespace Polymer {
      * @returns Generated class bound to the template
      *   provided
      */
-    function templatize(template: HTMLTemplateElement, owner: Polymer.PropertyEffects, options?: object|null): {new(): TemplateInstanceBase};
+    function templatize(template: HTMLTemplateElement, owner?: Polymer.PropertyEffects|null, options?: object|null): {new(): TemplateInstanceBase};
 
 
     /**