diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
index d0ad6db793a68..a4e45cd334bf2 100644
--- a/services/core/java/com/android/server/am/ActivityManagerService.java
+++ b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -10156,7 +10156,7 @@ public class ActivityManagerService extends IActivityManager.Stub
         }
     }
 
-    private volatile ArrayMap<String, long[]> mErrorClusterRecords = new ArrayMap<>();
+    private final ArrayMap<String, long[]> mErrorClusterRecords = new ArrayMap<>();
 
     /**
      * Write a description of an error (crash, WTF, ANR) to the drop box.
@@ -10189,16 +10189,18 @@ public class ActivityManagerService extends IActivityManager.Stub
         // Rate-limit how often we're willing to do the heavy lifting below to
         // collect and record logs; currently 5 logs per 10 second period per eventType.
         final long now = SystemClock.elapsedRealtime();
-        long[] errRecord = mErrorClusterRecords.get(eventType);
-        if (errRecord == null) {
-            errRecord = new long[2]; // [0]: startTime, [1]: count
-            mErrorClusterRecords.put(eventType, errRecord);
-        }
-        if (now - errRecord[0] > 10 * DateUtils.SECOND_IN_MILLIS) {
-            errRecord[0] = now;
-            errRecord[1] = 1L;
-        } else {
-            if (errRecord[1]++ >= 5) return;
+        synchronized (mErrorClusterRecords) {
+            long[] errRecord = mErrorClusterRecords.get(eventType);
+            if (errRecord == null) {
+                errRecord = new long[2]; // [0]: startTime, [1]: count
+                mErrorClusterRecords.put(eventType, errRecord);
+            }
+            if (now - errRecord[0] > 10 * DateUtils.SECOND_IN_MILLIS) {
+                errRecord[0] = now;
+                errRecord[1] = 1L;
+            } else {
+                if (errRecord[1]++ >= 5) return;
+            }
         }
 
         final StringBuilder sb = new StringBuilder(1024);