diff --git a/src/com/android/settings/network/MobileNetworkRepository.java b/src/com/android/settings/network/MobileNetworkRepository.java
index b0c85fc..381f3c1 100644
--- a/src/com/android/settings/network/MobileNetworkRepository.java
+++ b/src/com/android/settings/network/MobileNetworkRepository.java
@@ -295,7 +295,9 @@
     }
 
     public void removeRegister(MobileNetworkCallback mobileNetworkCallback) {
-        sCallbacks.remove(mobileNetworkCallback);
+        synchronized (this) {
+            sCallbacks.remove(mobileNetworkCallback);
+        }
         if (sCallbacks.isEmpty()) {
             mSubscriptionManager.removeOnSubscriptionsChangedListener(this);
             mAirplaneModeObserver.unRegister(mContext);