diff --git a/externs/closure-types.js b/externs/closure-types.js
index a4897db637..27e4bc7835 100644
--- a/externs/closure-types.js
+++ b/externs/closure-types.js
@@ -1377,7 +1377,7 @@ Polymer_ArraySelectorMixin.prototype.select = function(item){};
 Polymer_ArraySelectorMixin.prototype.selectIndex = function(idx){};
 /**
 * @interface
-* @extends {Polymer_PropertiesChanged}
+* @extends {Polymer_ElementMixin}
 */
 function Polymer_DisableUpgradeMixin(){}
 /**
diff --git a/lib/elements/dom-if.html b/lib/elements/dom-if.html
index d6ad8ca736..527ede86ae 100644
--- a/lib/elements/dom-if.html
+++ b/lib/elements/dom-if.html
@@ -179,7 +179,7 @@
       // Guard against element being detached while render was queued
       if (parentNode) {
         if (!this.__ctor) {
-          let template = this.querySelector('template');
+          let template = /** @type {HTMLTemplateElement} */(this.querySelector('template'));
           if (!template) {
             // Wait until childList changes and template should be there by then
             let observer = new MutationObserver(() => {
diff --git a/lib/elements/dom-repeat.html b/lib/elements/dom-repeat.html
index a68e68796f..4cd2189d8b 100644
--- a/lib/elements/dom-repeat.html
+++ b/lib/elements/dom-repeat.html
@@ -335,7 +335,7 @@
       // until ready, since won't have its template content handed back to
       // it until then
       if (!this.__ctor) {
-        let template = this.template = this.querySelector('template');
+        let template = this.template = /** @type {HTMLTemplateElement} */(this.querySelector('template'));
         if (!template) {
           // // Wait until childList changes and template should be there by then
           let observer = new MutationObserver(() => {
diff --git a/lib/mixins/disable-upgrade-mixin.html b/lib/mixins/disable-upgrade-mixin.html
index 4e7bfb4535..4f3a73c62d 100644
--- a/lib/mixins/disable-upgrade-mixin.html
+++ b/lib/mixins/disable-upgrade-mixin.html
@@ -35,7 +35,7 @@
    *
    * @mixinFunction
    * @polymer
-   * @appliesMixin Polymer.PropertiesChanged
+   * @appliesMixin Polymer.ElementMixin
    * @memberof Polymer
    */
   Polymer.DisableUpgradeMixin = Polymer.dedupingMixin((base) => {
@@ -43,9 +43,9 @@
     /**
      * @constructor
      * @extends {base}
-     * @implements {Polymer_PropertiesMixin}
+     * @implements {Polymer_ElementMixin}
      */
-    const superClass = Polymer.PropertiesMixin(base);
+    const superClass = Polymer.ElementMixin(base);
     /**
      * @polymer
      * @mixinClass
diff --git a/lib/mixins/properties-changed.html b/lib/mixins/properties-changed.html
index bd47e08c73..000c1374af 100644
--- a/lib/mixins/properties-changed.html
+++ b/lib/mixins/properties-changed.html
@@ -355,7 +355,7 @@
          * @return {boolean} true if changedProps is truthy
          */
         _shouldPropertiesChange(currentProps, changedProps, oldProps) { // eslint-disable-line no-unused-vars
-          return changedProps;
+          return Boolean(changedProps);
         }
 
         /**
diff --git a/types/lib/mixins/disable-upgrade-mixin.d.ts b/types/lib/mixins/disable-upgrade-mixin.d.ts
index 471a8462e4..80757fb860 100644
--- a/types/lib/mixins/disable-upgrade-mixin.d.ts
+++ b/types/lib/mixins/disable-upgrade-mixin.d.ts
@@ -31,7 +31,7 @@ declare namespace Polymer {
    *
    *     MyClass = Polymer.DisableUpgradeMixin(class extends BaseClass {...});
    */
-  function DisableUpgradeMixin<T extends new (...args: any[]) => {}>(base: T): T & DisableUpgradeMixinConstructor & Polymer.PropertiesChangedConstructor;
+  function DisableUpgradeMixin<T extends new (...args: any[]) => {}>(base: T): T & DisableUpgradeMixinConstructor & Polymer.ElementMixinConstructor & Polymer.PropertyEffectsConstructor & Polymer.TemplateStampConstructor & Polymer.PropertyAccessorsConstructor & Polymer.PropertiesChangedConstructor & Polymer.PropertiesMixinConstructor;
 
   interface DisableUpgradeMixinConstructor {
     new(...args: any[]): DisableUpgradeMixin;