diff --git a/services/core/java/com/android/server/AlarmManagerService.java b/services/core/java/com/android/server/AlarmManagerService.java
index 504a7ef..c5ce2fd 100644
--- a/services/core/java/com/android/server/AlarmManagerService.java
+++ b/services/core/java/com/android/server/AlarmManagerService.java
@@ -2769,7 +2769,9 @@
         }
 
         @Override public void onUidIdle(int uid) throws RemoteException {
-            removeForStoppedLocked(uid);
+            synchronized (mLock) {
+                removeForStoppedLocked(uid);
+            }
         }
     };