diff --git a/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py b/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
index 74ec2fecec..9a4fb719f4 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
+++ b/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
@@ -1258,6 +1258,7 @@ class ChibiOSHWDef(object):
 #ifndef CH_CFG_USE_DYNAMIC
 #define CH_CFG_USE_DYNAMIC FALSE
 #endif
+#define STM32_FLASH_DISABLE_ISR 0
 ''')
             if not self.env_vars['EXT_FLASH_SIZE_MB'] and not args.signed_fw:
                 f.write('''