diff --git a/lib/mixins/element-mixin.html b/lib/mixins/element-mixin.html
index 193f709fc4..58880fa3aa 100644
--- a/lib/mixins/element-mixin.html
+++ b/lib/mixins/element-mixin.html
@@ -32,7 +32,6 @@
    */
   let PolymerElementProperties; // eslint-disable-line no-unused-vars
 
-  /** @record */
   let PolymerElementConstructor = function(){}; // eslint-disable-line no-unused-vars
   /** @type {(string | undefined)} */
   PolymerElementConstructor.is;
@@ -139,7 +138,7 @@
         JSCompiler_renameProperty('__ownProperties', klass))) {
         klass.__ownProperties =
           klass.hasOwnProperty(JSCompiler_renameProperty('properties', klass)) ?
-          klass.properties : {};
+          /** @type PolymerElementConstructor */ (klass).properties : {};
       }
       return klass.__ownProperties;
     }
@@ -157,7 +156,7 @@
         JSCompiler_renameProperty('__ownObservers', klass))) {
         klass.__ownObservers =
           klass.hasOwnProperty(JSCompiler_renameProperty('observers', klass)) ?
-          klass.observers : [];
+          /** @type PolymerElementConstructor */ (klass).observers : [];
       }
       return klass.__ownObservers;
     }
@@ -188,7 +187,7 @@
      * (1) observedAttributes,
      * (2) class property default values
      *
-     * @param {HTMLElement} klass Element class
+     * @param {PolymerElementConstructor} klass Element class
      * @return {PolymerElementProperties} Flattened properties for this class
      * @private
      */
@@ -200,7 +199,7 @@
         let superCtor = Object.getPrototypeOf(klass.prototype).constructor;
         if (superCtor.prototype instanceof PolymerElement) {
           klass.__classProperties = Object.assign(
-            Object.create(propertiesForClass(superCtor)),
+            Object.create(propertiesForClass(/** @type PolymerElementConstructor */(superCtor))),
             klass.__classProperties);
         }
       }
@@ -213,7 +212,7 @@
      * the list returned from `propertiesForClass`.
      * This list is used in `_initializeProperties` to set property defaults.
      *
-     * @param {HTMLElement} klass Element class
+     * @param {PolymerElementConstructor} klass Element class
      * @return {PolymerElementProperties} Flattened properties for this class
      *   that have default values
      * @private
@@ -236,7 +235,7 @@
 
     /**
      * Returns true if a `klass` has finalized. Called in `ElementClass.finalize()`
-     * @param {HTMLElement} klass Element class
+     * @param {PolymerElementConstructor} klass Element class
      * @return {boolean} True if all metaprogramming for this class has been
      *   completed
      * @private
@@ -250,11 +249,11 @@
      * *all superclasses* are finalized by traversing the prototype chain
      * and calling `klass.finalize()`.
      *
-     * @param {HTMLElement} klass Element class
+     * @param {PolymerElementConstructor} klass Element class
      * @private
      */
     function finalizeClassAndSuper(klass) {
-      let proto = klass.prototype;
+      let proto = /** @type PolymerElementConstructor */ (klass).prototype;
       let superCtor = Object.getPrototypeOf(proto).constructor;
       if (superCtor.prototype instanceof PolymerElement) {
         superCtor.finalize();
@@ -268,12 +267,12 @@
      * for properties in `config` and the `template` as well as preparing the
      * `template` for stamping.
      *
-     * @param {HTMLElement} klass Element class
+     * @param {PolymerElementConstructor} klass Element class
      * @private
      */
     function finalizeClass(klass) {
       klass.__finalized = true;
-      let proto = klass.prototype;
+      let proto = /** @type PolymerElementConstructor */ (klass).prototype;
       if (klass.hasOwnProperty(
         JSCompiler_renameProperty('is', klass)) && klass.is) {
         Polymer.telemetry.register(proto);
@@ -287,7 +286,7 @@
         finalizeObservers(proto, observers, props);
       }
       // note: create "working" template that is finalized at instance time
-      let template = klass.template;
+      let template = /** @type PolymerElementConstructor */ (klass).template;
       if (template) {
         if (typeof template === 'string') {
           let t = document.createElement('template');
@@ -305,7 +304,7 @@
      * Leverages `PropertyEffects` to create property accessors and effects
      * supporting, observers, reflecting to attributes, change notification,
      * computed properties, and read only properties.
-     * @param {HTMLElement} proto Element class prototype to add accessors
+     * @param {PolymerElement} proto Element class prototype to add accessors
      *    and effects to
      * @param {Object} properties Flattened bag of property descriptors for
      *    this class
@@ -320,7 +319,7 @@
     /**
      * Configures a `proto` based on a `observers` array.
      * Leverages `PropertyEffects` to create observers.
-     * @param {HTMLElement} proto Element class prototype to add accessors
+     * @param {PolymerElement} proto Element class prototype to add accessors
      *   and effects to
      * @param {Object} observers Flattened array of observer descriptors for
      *   this class
@@ -384,7 +383,7 @@
      * and/or provide an advanced api for manipulating them.
      * Also consider adding warnings when an effect cannot be changed.
      *
-     * @param {HTMLElement} proto Element class prototype to add accessors
+     * @param {PolymerElement} proto Element class prototype to add accessors
      *   and effects to
      * @param {string} name Name of the property.
      * @param {Object} info Info object from which to create property effects.
@@ -426,7 +425,7 @@
      * The element name `is` and extends `ext` must be specified for ShadyCSS
      * style scoping.
      *
-     * @param {HTMLElement} proto Element class prototype to add accessors
+     * @param {PolymerElement} proto Element class prototype to add accessors
      *   and effects to
      * @param {HTMLTemplateElement} template Template to process and bind
      * @param {string} baseURI URL against which to resolve urls in
@@ -535,11 +534,12 @@
        */
       static get template() {
         if (!this.hasOwnProperty(JSCompiler_renameProperty('_template', this))) {
-          this._template = Polymer.DomModule.import(this.is, 'template') ||
+          this._template = Polymer.DomModule.import(
+            /** @type PolymerElementConstructor*/ (this).is, 'template') ||
             // note: implemented so a subclass can retrieve the super
             // template; call the super impl this way so that `this` points
             // to the superclass.
-            Object.getPrototypeOf(this.prototype).constructor.template;
+            Object.getPrototypeOf(/** @type PolymerElementConstructor*/ (this).prototype).constructor.template;
         }
         return this._template;
       }
@@ -557,9 +557,9 @@
        */
       static get importPath() {
         if (!this.hasOwnProperty(JSCompiler_renameProperty('_importPath', this))) {
-            const module = Polymer.DomModule.import(this.is);
+            const module = Polymer.DomModule.import(/** @type PolymerElementConstructor */ (this).is);
             this._importPath = module ? module.assetpath : '' ||
-            Object.getPrototypeOf(this.prototype).constructor.importPath;
+            Object.getPrototypeOf(/** @type PolymerElementConstructor*/ (this).prototype).constructor.importPath;
         }
         return this._importPath;
       }