diff --git a/ArduSub/system.cpp b/ArduSub/system.cpp
index f3639b96ca..55d571e553 100644
--- a/ArduSub/system.cpp
+++ b/ArduSub/system.cpp
@@ -275,8 +275,11 @@ bool Sub::should_log(uint32_t mask)
 #include <AP_ADSB/AP_ADSB.h>
 
 // dummy method to avoid linking AFS
+#if AP_ADVANCEDFAILSAFE_ENABLED
 bool AP_AdvancedFailsafe::gcs_terminate(bool should_terminate, const char *reason) { return false; }
 AP_AdvancedFailsafe *AP::advancedfailsafe() { return nullptr; }
+#endif
+
 #if HAL_ADSB_ENABLED
 // dummy method to avoid linking AP_Avoidance
 AP_Avoidance *AP::ap_avoidance() { return nullptr; }