diff --git a/lib/mixins/disable-upgrade-mixin.html b/lib/mixins/disable-upgrade-mixin.html
index 4f3a73c62d..a94418214e 100644
--- a/lib/mixins/disable-upgrade-mixin.html
+++ b/lib/mixins/disable-upgrade-mixin.html
@@ -7,6 +7,7 @@
 Code distributed by Google as part of the polymer project is also
 subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
 -->
+<link rel="import" href="element-mixin.html">
 <script>
 (function() {
   'use strict';
diff --git a/test/unit/disable-upgrade.html b/test/unit/disable-upgrade.html
index 6d7c6af1d3..f5ad09dd49 100644
--- a/test/unit/disable-upgrade.html
+++ b/test/unit/disable-upgrade.html
@@ -32,27 +32,28 @@ <h2 id="element">[[prop]]</h2>
     </template>
 
     <script>
-      const Disabled = Polymer.DisableUpgradeMixin(class extends Polymer.Element {
-        static get is() { return 'x-disabled'; }
-        static get properties() {
-          return {
-            prop: {
-              type: String
-            }
-          };
-        }
-        constructor() {
-          super();
-          this.prop = 'enabled!';
-        }
+      addEventListener('WebComponentsReady', function() {
+        const Disabled = Polymer.DisableUpgradeMixin(class extends Polymer.Element {
+          static get is() { return 'x-disabled'; }
+          static get properties() {
+            return {
+              prop: {
+                type: String
+              }
+            };
+          }
+          constructor() {
+            super();
+            this.prop = 'enabled!';
+          }
 
-        ready() {
-          super.ready();
-          this.enabled = true;
-        }
+          ready() {
+            super.ready();
+            this.enabled = true;
+          }
+        });
+        customElements.define(Disabled.is, Disabled);
       });
-      customElements.define(Disabled.is, Disabled);
-
     </script>
 
   </dom-module>
@@ -72,7 +73,7 @@ <h2 id="element">[[prop]]</h2>
       </template>
 
       <script>
-        (function() {
+        addEventListener('WebComponentsReady', function() {
 
           // enable disable upgrade!
           const polymerClass = Polymer.Class;
@@ -111,7 +112,7 @@ <h2 id="element">[[prop]]</h2>
             }
           });
 
-        })();
+        });
       </script>
 
     </dom-module>
@@ -125,20 +126,21 @@ <h2 id="element">[[prop]]</h2>
     </template>
 
     <script>
-      class MyElement extends Polymer.Element {
-        static get is() { return 'my-element'; }
-        static get properties() {
-          return {
-            upgradeDisabled: {value: true}
-          };
-        }
-        enable() {
-          this.$.disabledEl.removeAttribute('disable-upgrade');
-          this.upgradeDisabled = false;
+      addEventListener('WebComponentsReady', function() {
+        class MyElement extends Polymer.Element {
+          static get is() { return 'my-element'; }
+          static get properties() {
+            return {
+              upgradeDisabled: {value: true}
+            };
+          }
+          enable() {
+            this.$.disabledEl.removeAttribute('disable-upgrade');
+            this.upgradeDisabled = false;
+          }
         }
-      }
-      customElements.define(MyElement.is, MyElement);
-
+        customElements.define(MyElement.is, MyElement);
+      });
     </script>
 
   </dom-module>
@@ -155,16 +157,18 @@ <h2 id="element">[[prop]]</h2>
     </template>
 
     <script>
-      Polymer({
-        is: 'my-element-legacy',
-        properties: {
-          upgradeDisabled: { type: String, value: true }
-        },
-        enable() {
-          this.$.disabledEl.removeAttribute('disable-upgrade');
-          this.$.disabledRegEl.removeAttribute('disable-upgrade');
-          this.upgradeDisabled = false;
-        }
+      addEventListener('WebComponentsReady', function() {
+        Polymer({
+          is: 'my-element-legacy',
+          properties: {
+            upgradeDisabled: { type: String, value: true }
+          },
+          enable() {
+            this.$.disabledEl.removeAttribute('disable-upgrade');
+            this.$.disabledRegEl.removeAttribute('disable-upgrade');
+            this.upgradeDisabled = false;
+          }
+        });
       });
     </script>