diff --git a/tools/lock_agent/java/com/android/lock_checker/LockHook.java b/tools/lock_agent/java/com/android/lock_checker/LockHook.java
index 95b3181..efab1d2 100644
--- a/tools/lock_agent/java/com/android/lock_checker/LockHook.java
+++ b/tools/lock_agent/java/com/android/lock_checker/LockHook.java
@@ -66,7 +66,8 @@
 
     static final StatLogger sStats = new StatLogger(new String[] { "on-thread", });
 
-    private static final ConcurrentLinkedQueue<Object> sViolations = new ConcurrentLinkedQueue<>();
+    private static final ConcurrentLinkedQueue<Violation> sViolations =
+            new ConcurrentLinkedQueue<>();
     private static final int MAX_VIOLATIONS = 50;
 
     private static final LockChecker[] sCheckers;
@@ -101,8 +102,8 @@
         }
     }
 
-    static void wtf(String message) {
-        sHandler.wtf(message);
+    static void wtf(Violation v) {
+        sHandler.wtf(v);
     }
 
     static void doCheckOnThisThread(boolean check) {
@@ -151,10 +152,10 @@
             super(looper);
         }
 
-        public void wtf(String msg) {
+        public void wtf(Violation v) {
             sDoCheck.set(false);
             SomeArgs args = SomeArgs.obtain();
-            args.arg1 = msg;
+            args.arg1 = v;
             obtainMessage(MSG_WTF, args).sendToTarget();
             sDoCheck.set(true);
         }
@@ -164,13 +165,18 @@
             switch (msg.what) {
                 case MSG_WTF:
                     SomeArgs args = (SomeArgs) msg.obj;
-                    Log.wtf(TAG, (String) args.arg1);
+                    handleViolation((Violation) args.arg1);
                     args.recycle();
                     break;
             }
         }
     }
 
+    private static void handleViolation(Violation v) {
+        String msg = v.toString();
+        Log.wtf(TAG, msg);
+    }
+
     /**
      * Generates a hash for a given stacktrace of a {@link Throwable}.
      */
@@ -224,8 +230,10 @@
         }
     }
 
-    static void addViolation(Object o) {
-        sViolations.offer(o);
+    static void addViolation(Violation v) {
+        wtf(v);
+
+        sViolations.offer(v);
         while (sViolations.size() > MAX_VIOLATIONS) {
             sViolations.poll();
         }
@@ -287,4 +295,7 @@
 
         void dump(PrintWriter pw);
     }
+
+    interface Violation {
+    }
 }
diff --git a/tools/lock_agent/java/com/android/lock_checker/OnThreadLockChecker.java b/tools/lock_agent/java/com/android/lock_checker/OnThreadLockChecker.java
index 0f3a285..e4e7211 100644
--- a/tools/lock_agent/java/com/android/lock_checker/OnThreadLockChecker.java
+++ b/tools/lock_agent/java/com/android/lock_checker/OnThreadLockChecker.java
@@ -220,7 +220,7 @@
         heldLocks.remove(index);
     }
 
-    private static class Violation {
+    private static class Violation implements LockHook.Violation {
         int mSelfTid;
         String mSelfName;
         Object mAlreadyHeld;
@@ -323,7 +323,6 @@
         if (LockHook.shouldDumpStacktrace(mStacktraceHasher.get(), mDumpedStacktraceHashes,
                 Boolean.TRUE, v.mStack, 0, to)) {
             mNumDetectedUnique.incrementAndGet();
-            LockHook.wtf(v.toString());
             LockHook.addViolation(v);
         }
     }