diff --git a/aos/realtime.h b/aos/realtime.h
index a6b4223..bc80ee5 100644
--- a/aos/realtime.h
+++ b/aos/realtime.h
@@ -28,6 +28,8 @@
 
 void LockAllMemory();
 
+void ExpandStackSize();
+
 }  // namespace aos
 
 #endif  // AOS_REALTIME_H_