diff --git a/src/lib/bind/accessors.html b/src/lib/bind/accessors.html
index 58e301f5cf..29e7541103 100644
--- a/src/lib/bind/accessors.html
+++ b/src/lib/bind/accessors.html
@@ -23,7 +23,8 @@
         value = value === undefined ? this[source] : value;
         event = event || Polymer.CaseMap.camelToDashCase(source) + '-changed';
         this.fire(event, {value: value},
-          {bubbles: false, cancelable: false, _useCache: Polymer.Settings.eventDataCache || !CustomElements.isIE});
+          {bubbles: false, cancelable: false, _useCache:
+            Polymer.Settings.eventDataCache || !Polymer.Settings.isIE});
       },
 
       // TODO(sjmiles): removing _notifyListener from here breaks accessors.html
diff --git a/src/lib/settings.html b/src/lib/settings.html
index 6902845201..09b2a11576 100644
--- a/src/lib/settings.html
+++ b/src/lib/settings.html
@@ -55,6 +55,8 @@
       settings.useNativeCSSProperties = settings.hasNativeCSSProperties &&
         settings.lazyRegister && settings.useNativeCSSProperties;
 
+      settings.isIE = navigator.userAgent.match('Trident');
+
       return settings;
     })()
   };
diff --git a/src/standard/events.html b/src/standard/events.html
index a795526fb0..06260c54bd 100644
--- a/src/standard/events.html
+++ b/src/standard/events.html
@@ -108,7 +108,7 @@
       var bl = hbl.get(target);
       if (!bl) {
         bl = {};
-        if( !CustomElements.isIE || target != window ) {
+        if( !Polymer.Settings.isIE || target != window ) {
           hbl.set(target, bl);
         }
       }
diff --git a/src/standard/notify-path.html b/src/standard/notify-path.html
index e850b2304f..9328a5b085 100644
--- a/src/standard/notify-path.html
+++ b/src/standard/notify-path.html
@@ -376,7 +376,8 @@
         this.fire(eventName, {
           path: path,
           value: value
-        }, {bubbles: false, _useCache: Polymer.Settings.eventDataCache || !CustomElements.isIE});
+        }, {bubbles: false, _useCache: Polymer.Settings.eventDataCache ||
+          !Polymer.Settings.isIE});
       },
 
       _EVENT_CHANGED: '-changed',