diff --git a/libraries/GCS_MAVLink/GCS_MAVLink.h b/libraries/GCS_MAVLink/GCS_MAVLink.h
index f929ab6097..2c27ff46b7 100644
--- a/libraries/GCS_MAVLink/GCS_MAVLink.h
+++ b/libraries/GCS_MAVLink/GCS_MAVLink.h
@@ -7,7 +7,8 @@
 #define GCS_MAVLink_h
 
 #include <AP_HAL.h>
-#include <AP_Param.h>
+#include <AP_Param.h>
+#include <AP_Math.h>
 
 // we have separate helpers disabled to make it possible
 // to select MAVLink 1.0 in the arduino GUI build