diff --git a/services/sync/modules/engines/history.js b/services/sync/modules/engines/history.js
index 96c321c560ba..a2fc5fc811e0 100644
--- a/services/sync/modules/engines/history.js
+++ b/services/sync/modules/engines/history.js
@@ -492,7 +492,7 @@ HistoryTracker.prototype = {
   },
 
   _init: function HT__init() {
-    this.__proto__.__proto__._init.call(this);
+    Tracker._init.call(this);
     this._hsvc.addObserver(this, false);
   },