diff --git a/libraries/AP_GPS/GPS_Backend.h b/libraries/AP_GPS/GPS_Backend.h
index 70f4cb36fc215..2a70a1c57153e 100644
--- a/libraries/AP_GPS/GPS_Backend.h
+++ b/libraries/AP_GPS/GPS_Backend.h
@@ -71,7 +71,9 @@ class AP_GPS_Backend
 #if HAL_GCS_ENABLED
     //MAVLink methods
     virtual bool supports_mavlink_gps_rtk_message() const { return false; }
+#if AP_GPS_GPS_RTK_SENDING_ENABLED || AP_GPS_GPS2_RTK_SENDING_ENABLED
     virtual void send_mavlink_gps_rtk(mavlink_channel_t chan);
+#endif
     virtual void handle_msg(const mavlink_message_t &msg) { return ; }
 #endif