diff --git a/libraries/AP_HAL_ChibiOS/hwdef/skyviper-journey/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/skyviper-journey/hwdef.dat
index ab757c1706..188914fade 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/skyviper-journey/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/skyviper-journey/hwdef.dat
@@ -9,6 +9,7 @@ APJ_BOARD_ID 9
 # crystal frequency
 OSCILLATOR_HZ 24000000
 
+define HAL_CUSTOM_CLOCK_TREE
 STM32_HSE_ENABLED FALSE
 STM32_PLLM_VALUE 16
 STM32_PLLN_VALUE 384
@@ -130,7 +131,7 @@ define HAL_BARO_20789_I2C_ADDR_ICM   0x68
 # unstick 20789 on I2C on boot
 define HAL_I2C_CLEAR_BUS
 
-env DEFINES CONFIG_HAL_BOARD_SUBTYPE='HAL_BOARD_SUBTYPE_CHIBIOS_SKYVIPER_F412'
+define CONFIG_HAL_BOARD_SUBTYPE HAL_BOARD_SUBTYPE_CHIBIOS_SKYVIPER_F412
 
 # the web UI uses an abin file for firmware uploads
 env BUILD_ABIN True