diff --git a/libraries/AP_HAL/board/chibios.h b/libraries/AP_HAL/board/chibios.h
index 16cd1960eb..0a938acfa3 100644
--- a/libraries/AP_HAL/board/chibios.h
+++ b/libraries/AP_HAL/board/chibios.h
@@ -105,7 +105,7 @@
 
 // we support RC serial for BLHeli pass-thru
 #ifndef HAL_SUPPORT_RCOUT_SERIAL
-#define HAL_SUPPORT_RCOUT_SERIAL 1
+#define HAL_SUPPORT_RCOUT_SERIAL !defined(HAL_BUILD_AP_PERIPH)
 #endif
 
 // by default assume first I2C bus is internal