diff --git a/media/bufferpool/2.0/IObserver.hal b/media/bufferpool/2.0/IObserver.hal
index a998836..62f247e 100644
--- a/media/bufferpool/2.0/IObserver.hal
+++ b/media/bufferpool/2.0/IObserver.hal
@@ -29,6 +29,7 @@
      * message.
      *
      * @param connectionId the connection Id of the specific buffer pool client
+     * @param msgId Id of the most recent message
      */
-    oneway onMessage(int64_t connectionId);
+    oneway onMessage(int64_t connectionId, uint32_t msgId);
 };