diff --git a/libraries/GCS_MAVLink/GCS_Common.cpp b/libraries/GCS_MAVLink/GCS_Common.cpp
index 03dfa5f0df..009c698a2f 100644
--- a/libraries/GCS_MAVLink/GCS_Common.cpp
+++ b/libraries/GCS_MAVLink/GCS_Common.cpp
@@ -22,6 +22,7 @@
 #include <AP_Airspeed/AP_Airspeed.h>
 #include <AP_Gripper/AP_Gripper.h>
 #include <AP_BLHeli/AP_BLHeli.h>
+#include <AP_Common/Semaphore.h>
 
 #include "GCS.h"