diff --git a/include/gui/SensorEventQueue.h b/include/gui/SensorEventQueue.h
index 4e8a2d2..019308d 100644
--- a/include/gui/SensorEventQueue.h
+++ b/include/gui/SensorEventQueue.h
@@ -27,7 +27,7 @@
 #include <gui/BitTube.h>
 
 // ----------------------------------------------------------------------------
-#define WAKE_UP_SENSOR_EVENT_NEEDS_ACK (1 << 31)
+#define WAKE_UP_SENSOR_EVENT_NEEDS_ACK (1U << 31)
 struct ALooper;
 struct ASensorEvent;