diff --git a/services/core/java/com/android/server/PersistentDataBlockService.java b/services/core/java/com/android/server/PersistentDataBlockService.java
index 35a740263a8eb..43fda5f0245e3 100644
--- a/services/core/java/com/android/server/PersistentDataBlockService.java
+++ b/services/core/java/com/android/server/PersistentDataBlockService.java
@@ -29,6 +29,7 @@ import android.service.persistentdata.IPersistentDataBlockService;
 import android.util.Slog;
 
 import com.android.internal.R;
+import com.android.internal.annotations.GuardedBy;
 
 import libcore.io.IoUtils;
 
@@ -76,6 +77,8 @@ public class PersistentDataBlockService extends SystemService {
 
     private int mAllowedUid = -1;
     private long mBlockDeviceSize;
+
+    @GuardedBy("mLock")
     private boolean mIsWritable = true;
 
     public PersistentDataBlockService(Context context) {