diff --git a/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py b/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
index 9b44a112a9..4f611132cb 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
+++ b/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
@@ -455,6 +455,8 @@ def write_ldscript(fname):
     flash_reserve_start = get_config(
         'FLASH_RESERVE_START_KB', default=16, type=int)
 
+    env_vars['FLASH_RESERVE_START_KB'] = str(flash_reserve_start)
+
     # space to reserve for storage at end of flash
     flash_reserve_end = get_config('FLASH_RESERVE_END_KB', default=0, type=int)