diff --git a/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py b/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
index a803a39f82..2e7b41ca1b 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
+++ b/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
@@ -3144,6 +3144,9 @@ def add_iomcu_firmware_defaults(f):
 #define AP_FAULTHANDLER_DEBUG_VARIABLES_ENABLED 0
 #endif
 
+// disable some protocols on iomcu:
+#define AP_RCPROTOCOL_FASTSBUS_ENABLED 0
+
 // end IOMCU Firmware defaults
 ''')