diff --git a/libraries/AP_HAL_ChibiOS/hwdef/Pixhawk6X-PPPGW/hwdef-bl.dat b/libraries/AP_HAL_ChibiOS/hwdef/Pixhawk6X-PPPGW/hwdef-bl.dat
index 43181e9a48..b78dd641a8 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/Pixhawk6X-PPPGW/hwdef-bl.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/Pixhawk6X-PPPGW/hwdef-bl.dat
@@ -32,8 +32,7 @@ define CH_CFG_USE_EVENTS 1
 undef CH_CFG_USE_SEMAPHORES
 define CH_CFG_USE_SEMAPHORES 1
 
-undef SERIAL_ORDER
-SERIAL_ORDER
+SERIAL_ORDER OTG1
 
 ROMFS_WILDCARD Tools/AP_Bootloader/Web/*.html
 env ROMFS_UNCOMPRESSED True