--- a/mobile/android/base/java/org/mozilla/gecko/MediaPlayerManager.java
+++ b/mobile/android/base/java/org/mozilla/gecko/MediaPlayerManager.java
@@ -182,18 +182,19 @@ public class MediaPlayerManager extends 
                 debug("onRouteRemoved: route=" + route);
 
                 // Remove from media player list.
                 players.remove(route.getId());
                 GeckoAppShell.notifyObservers("MediaPlayer:Removed", route.getId());
                 updatePresentation();
 
                 // Remove from presentation display list.
-                displays.remove(route.getId());
-                GeckoAppShell.notifyObservers("AndroidCastDevice:Removed", route.getId());
+                if (displays.remove(route.getId()) != null) {
+                    GeckoAppShell.notifyObservers("AndroidCastDevice:Removed", route.getId());
+                }
             }
 
             @Override
             public void onRouteSelected(MediaRouter router, MediaRouter.RouteInfo route) {
                 updatePresentation();
             }
 
             @Override