diff --git a/libraries/AP_HAL_ChibiOS/HAL_ChibiOS_Class.cpp b/libraries/AP_HAL_ChibiOS/HAL_ChibiOS_Class.cpp
index c221b482b0..e621d7fc58 100644
--- a/libraries/AP_HAL_ChibiOS/HAL_ChibiOS_Class.cpp
+++ b/libraries/AP_HAL_ChibiOS/HAL_ChibiOS_Class.cpp
@@ -48,7 +48,7 @@
 #define HAL_SCHEDULER_LOOP_DELAY_ENABLED 1
 #endif
 
-#ifndef HAL_NO_UARTDRIVER
+#if AP_HAL_UARTDRIVER_ENABLED
 static HAL_SERIAL0_DRIVER;
 static HAL_SERIAL1_DRIVER;
 static HAL_SERIAL2_DRIVER;
diff --git a/libraries/AP_HAL_ChibiOS/UARTDriver.cpp b/libraries/AP_HAL_ChibiOS/UARTDriver.cpp
index 4bc97e1414..035444cbee 100644
--- a/libraries/AP_HAL_ChibiOS/UARTDriver.cpp
+++ b/libraries/AP_HAL_ChibiOS/UARTDriver.cpp
@@ -18,7 +18,7 @@
 
 #define HAL_FORWARD_OTG2_SERIAL_LOCK_KEY 0x23565283UL
 
-#if CONFIG_HAL_BOARD == HAL_BOARD_CHIBIOS && !defined(HAL_NO_UARTDRIVER)
+#if CONFIG_HAL_BOARD == HAL_BOARD_CHIBIOS && AP_HAL_UARTDRIVER_ENABLED
 
 #include <hal.h>
 #include "UARTDriver.h"
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/Hitec-Airspeed/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/Hitec-Airspeed/hwdef.dat
index 02e4dc43f3..b9e7df2f27 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/Hitec-Airspeed/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/Hitec-Airspeed/hwdef.dat
@@ -29,7 +29,7 @@ FLASH_SIZE_KB 128
 # SERIAL_ORDER USART1
 SERIAL_ORDER
 define HAL_USE_UART FALSE
-define HAL_NO_UARTDRIVER TRUE
+define AP_HAL_UARTDRIVER_ENABLED 0
 
 define HAL_CAN_POOL_SIZE 6000
 
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/iomcu/hwdef.inc b/libraries/AP_HAL_ChibiOS/hwdef/iomcu/hwdef.inc
index 8387878750..eb1854f5e0 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/iomcu/hwdef.inc
+++ b/libraries/AP_HAL_ChibiOS/hwdef/iomcu/hwdef.inc
@@ -117,7 +117,7 @@ define __FPU_PRESENT 0
 
 define HAL_USE_RTC FALSE
 define HAL_NO_FLASH_SUPPORT TRUE
-define HAL_NO_UARTDRIVER TRUE
+define AP_HAL_UARTDRIVER_ENABLED 0
 define HAL_LOGGING_ENABLED 0
 
 define DMA_RESERVE_SIZE 0
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py b/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
index 935db8536f..211e4443c7 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
+++ b/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
@@ -1221,7 +1221,6 @@ class ChibiOSHWDef(object):
 #define HAL_BOOTLOADER_BUILD TRUE
 #define HAL_USE_ADC FALSE
 #define HAL_USE_EXT FALSE
-#define HAL_NO_UARTDRIVER
 #define HAL_NO_PRINTF
 #define HAL_NO_CCM
 #define HAL_USE_I2C FALSE
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/scripts/defaults_bootloader.h b/libraries/AP_HAL_ChibiOS/hwdef/scripts/defaults_bootloader.h
index 205a200230..91f9de9ae3 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/scripts/defaults_bootloader.h
+++ b/libraries/AP_HAL_ChibiOS/hwdef/scripts/defaults_bootloader.h
@@ -10,6 +10,11 @@
 #define HAL_GYROFFT_ENABLED 0
 #endif
 
+// bootloaders use serial directly:
+#ifndef AP_HAL_UARTDRIVER_ENABLED
+#define AP_HAL_UARTDRIVER_ENABLED 0
+#endif
+
 // bootloaders don't talk to the GCS:
 #ifndef HAL_GCS_ENABLED
 #define HAL_GCS_ENABLED 0
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/sw-nav-f405/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/sw-nav-f405/hwdef.dat
index 18e17fe682..b525c809fd 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/sw-nav-f405/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/sw-nav-f405/hwdef.dat
@@ -51,7 +51,7 @@ PA15 GPIO_CAN1_SILENT OUTPUT PUSHPULL SPEED_LOW LOW
 
 # disable serial
 define HAL_USE_SERIAL FALSE
-define HAL_NO_UARTDRIVER TRUE
+define AP_HAL_UARTDRIVER_ENABLED 0
 
 define HAL_USE_ADC FALSE