diff --git a/audio/effect/6.0/IEffect.hal b/audio/effect/6.0/IEffect.hal
index b35afee..f4c50a2 100644
--- a/audio/effect/6.0/IEffect.hal
+++ b/audio/effect/6.0/IEffect.hal
@@ -407,9 +407,12 @@
 
     /**
      * Called by the framework to deinitialize the effect and free up
-     * all the currently allocated resources. It is recommended to close
+     * all currently allocated resources. It is recommended to close
      * the effect on the client side as soon as it is becomes unused.
      *
+     * The client must ensure that this function is not called while
+     * audio data is being transferred through the effect's message queues.
+     *
      * @return retval OK in case the success.
      *                INVALID_STATE if the effect was already closed.
      */