diff --git a/externs/closure-types.js b/externs/closure-types.js
index 6fc6e3466a..7db4746320 100644
--- a/externs/closure-types.js
+++ b/externs/closure-types.js
@@ -24,6 +24,10 @@ function Polymer_PropertiesChanged(){}
 Polymer_PropertiesChanged.prototype._createPropertyAccessor = function(property, readOnly){};
 /**
 * @param {string} property Name of the property
+*/
+Polymer_PropertiesChanged.prototype._addPropertyToAttributeMap = function(property){};
+/**
+* @param {string} property Name of the property
 * @param {boolean=} readOnly When true, no setter is created
 * @return {void}
 */
diff --git a/types/lib/mixins/properties-changed.d.ts b/types/lib/mixins/properties-changed.d.ts
index b43e976f00..ffb670164b 100644
--- a/types/lib/mixins/properties-changed.d.ts
+++ b/types/lib/mixins/properties-changed.d.ts
@@ -77,6 +77,15 @@ declare namespace Polymer {
      */
     _createPropertyAccessor(property: string, readOnly?: boolean): void;
 
+    /**
+     * Adds the given `property` to a map matching attribute names
+     * to property names, using `attributeNameForProperty`. This map is
+     * used when deserializing attribute values to properties.
+     *
+     * @param property Name of the property
+     */
+    _addPropertyToAttributeMap(property: string): any;
+
     /**
      * Defines a property accessor for the given property.
      *