diff --git a/ArduSub/GCS_Sub.cpp b/ArduSub/GCS_Sub.cpp
index 52b342f8b9..1b25b10242 100644
--- a/ArduSub/GCS_Sub.cpp
+++ b/ArduSub/GCS_Sub.cpp
@@ -99,5 +99,7 @@ void GCS_Sub::update_vehicle_sensor_status_flags()
 #endif
 }
 
+// avoid building/linking LTM:
+void AP_LTM_Telem::init() {};
 // avoid building/linking Devo:
 void AP_DEVO_Telem::init() {};