diff --git a/platform/commonUI/mobile/src/AgentService.js b/platform/commonUI/mobile/src/AgentService.js
index 1f6fcb63e3..26bb173ee7 100644
--- a/platform/commonUI/mobile/src/AgentService.js
+++ b/platform/commonUI/mobile/src/AgentService.js
@@ -41,7 +41,7 @@ define(
          */
         function AgentService($window) {
             var userAgent = $window.navigator.userAgent,
-                matches = ua.match(/iPad|iPhone|Android/i) || [];
+                matches = userAgent.match(/iPad|iPhone|Android/i) || [];
 
             this.mobileName = matches[0];
             this.$window = $window;
@@ -79,7 +79,7 @@ define(
          * @returns {boolean} true in portrait mode
          */
         AgentService.prototype.isPortrait = function () {
-            return $window.innerWidth < $window.innerHeight;
+            return this.$window.innerWidth < this.$window.innerHeight;
         };
 
         /**
diff --git a/platform/commonUI/mobile/src/MobileBrowseTreeController.js b/platform/commonUI/mobile/src/MobileBrowseTreeController.js
index ca1abeb50a..a88aa63088 100644
--- a/platform/commonUI/mobile/src/MobileBrowseTreeController.js
+++ b/platform/commonUI/mobile/src/MobileBrowseTreeController.js
@@ -43,7 +43,10 @@ define(
             }
 
             if (agentService.isMobile()) {
-                navigationService.listen(changeObject);
+                navigationService.addListener(changeObject);
+                $scope.$on("$destroy", function () {
+                    navigationService.removeListener(changeObject);
+                });
             }
 
             this.state = true;