diff --git a/src/lib/base.html b/src/lib/base.html
index a6c53a3b14..9b3945df7f 100644
--- a/src/lib/base.html
+++ b/src/lib/base.html
@@ -64,7 +64,7 @@
     },
 
     createdCallback: function() {
-      if (Polymer.Settings.disableUpgradeEnabled) {
+      if (settings.disableUpgradeEnabled) {
         if (this.hasAttribute('disable-upgrade')) {
           this._propertySetter = disableUpgradePropertySetter;
           this.__data__ = {};
@@ -302,7 +302,12 @@
   Polymer.BaseDescriptors = {};
 
   var disableUpgradePropertySetter;
-  if (Polymer.Settings.disableUpgradeEnabled) {
+
+  if (settings.disableUpgradeEnabled) {
+
+    disableUpgradePropertySetter = function(property, value) {
+      this.__data__[property] = value;
+    }
 
     var origAttributeChangedCallback = Polymer.Base.attributeChangedCallback;
     Polymer.Base.attributeChangedCallback = function(name, oldValue, newValue) {
@@ -314,10 +319,6 @@
       origAttributeChangedCallback.call(this, name, oldValue, newValue);
     }
 
-    disableUpgradePropertySetter = function(property, value) {
-      this.__data__[property] = value;
-    }
-
   }
 
   if (window.CustomElements) {