diff --git a/ArduSub/GCS_Mavlink.h b/ArduSub/GCS_Mavlink.h
index c6e416c575..921b51f4b0 100644
--- a/ArduSub/GCS_Mavlink.h
+++ b/ArduSub/GCS_Mavlink.h
@@ -40,6 +40,8 @@ protected:
 
     uint64_t capabilities() const override;
 
+    uint8_t get_battery_remaining_percentage() override { return -1; };
+
 private:
 
     void handleMessage(const mavlink_message_t &msg) override;