diff --git a/libraries/GCS_MAVLink/GCS.h b/libraries/GCS_MAVLink/GCS.h
index 0157265c6f..6115fff7db 100644
--- a/libraries/GCS_MAVLink/GCS.h
+++ b/libraries/GCS_MAVLink/GCS.h
@@ -162,7 +162,7 @@ public:
     void send_heartbeat(uint8_t type, uint8_t base_mode, uint32_t custom_mode, uint8_t system_status);
     void send_servo_output_raw(bool hil);
     static void send_collision_all(const AP_Avoidance::Obstacle &threat, MAV_COLLISION_ACTION behaviour);
-    void send_accelcal_vehicle_position(uint8_t position);
+    void send_accelcal_vehicle_position(uint32_t position);
 
     // return a bitmap of active channels. Used by libraries to loop
     // over active channels to send to all active channels    
diff --git a/libraries/GCS_MAVLink/GCS_Common.cpp b/libraries/GCS_MAVLink/GCS_Common.cpp
index 21a606d640..2129c44339 100644
--- a/libraries/GCS_MAVLink/GCS_Common.cpp
+++ b/libraries/GCS_MAVLink/GCS_Common.cpp
@@ -1509,7 +1509,7 @@ void GCS_MAVLINK::send_collision_all(const AP_Avoidance::Obstacle &threat, MAV_C
     }
 }
 
-void GCS_MAVLINK::send_accelcal_vehicle_position(uint8_t position)
+void GCS_MAVLINK::send_accelcal_vehicle_position(uint32_t position)
 {
     if (HAVE_PAYLOAD_SPACE(chan, COMMAND_LONG)) {
         mavlink_msg_command_long_send(