diff --git a/include/gui/SensorEventQueue.h b/include/gui/SensorEventQueue.h
index 019308d..02b3d38 100644
--- a/include/gui/SensorEventQueue.h
+++ b/include/gui/SensorEventQueue.h
@@ -86,6 +86,7 @@
     ASensorEvent* mRecBuffer;
     size_t mAvailable;
     size_t mConsumed;
+    uint32_t mNumAcksToSend;
 };
 
 // ----------------------------------------------------------------------------