diff --git a/externs/polymer-externs.js b/externs/polymer-externs.js
index c3b7cdfaaa..c47d9a7a06 100644
--- a/externs/polymer-externs.js
+++ b/externs/polymer-externs.js
@@ -15,19 +15,19 @@
 
 /**
  * @typedef {{
- * type: !Function,
- * value: *,
- * readOnly: (boolean | undefined),
- * computed: (string | undefined),
- * reflectToAttribute: (boolean | undefined),
- * notify: (boolean | undefined),
- * observer: (string | function(*,*) | undefined)
+ *   type: !Function,
+ *   value: (* | undefined),
+ *   readOnly: (boolean | undefined),
+ *   computed: (string | undefined),
+ *   reflectToAttribute: (boolean | undefined),
+ *   notify: (boolean | undefined),
+ *   observer: (string | function(this:?, ?, ?) | undefined)
  * }}
  */
 let PolymerElementPropertiesMeta;
 
 /**
- * @typedef {Object<string, !PolymerElementPropertiesMeta>}
+ * @typedef {Object<string, !Function|!PolymerElementPropertiesMeta>}
  */
 let PolymerElementProperties;
 
@@ -69,9 +69,6 @@ PropertiesMixinConstructor.properties;
  */
 function Polymer(init){}
 
-/** @type {PolymerElementProperties} */
-Polymer.ElementProperties;
-
 /**
  * @type {(function(*,string,string,Node):*)|undefined}
  */
@@ -120,4 +117,4 @@ PolymerElement.prototype.registered = function() {};
 /** On attached to the DOM callback. */
 PolymerElement.prototype.attached = function() {};
 /** On detached from the DOM callback. */
-PolymerElement.prototype.detached = function() {};
+PolymerElement.prototype.detached = function() {};
\ No newline at end of file