diff --git a/libraries/AP_RCProtocol/AP_RCProtocol.h b/libraries/AP_RCProtocol/AP_RCProtocol.h
index 9d17e96739..b75a53fdee 100644
--- a/libraries/AP_RCProtocol/AP_RCProtocol.h
+++ b/libraries/AP_RCProtocol/AP_RCProtocol.h
@@ -24,14 +24,6 @@
 #define MAX_RCIN_CHANNELS 18
 #define MIN_RCIN_CHANNELS  5
 
-#ifndef AP_RCPROTOCOL_FASTSBUS_ENABLED
-  #ifdef IOMCU_FW
-    #define AP_RCPROTOCOL_FASTSBUS_ENABLED 0
-  #else
-    #define AP_RCPROTOCOL_FASTSBUS_ENABLED 1
-  #endif
-#endif
-
 class AP_RCProtocol_Backend;
 
 class AP_RCProtocol {
diff --git a/libraries/AP_RCProtocol/AP_RCProtocol_config.h b/libraries/AP_RCProtocol/AP_RCProtocol_config.h
index f489879bce..5aa88fe80e 100644
--- a/libraries/AP_RCProtocol/AP_RCProtocol_config.h
+++ b/libraries/AP_RCProtocol/AP_RCProtocol_config.h
@@ -7,6 +7,10 @@
 #define AP_RCPROTOCOL_BACKEND_DEFAULT_ENABLED 1
 #endif
 
+#ifndef AP_RCPROTOCOL_FASTSBUS_ENABLED
+#define AP_RCPROTOCOL_FASTSBUS_ENABLED AP_RCPROTOCOL_BACKEND_DEFAULT_ENABLED
+#endif
+
 #ifndef AP_RCPROTOCOL_FPORT_ENABLED
 #define AP_RCPROTOCOL_FPORT_ENABLED AP_RCPROTOCOL_BACKEND_DEFAULT_ENABLED && AP_FRSKY_SPORT_TELEM_ENABLED
 #endif