diff --git a/libraries/AP_HAL_ChibiOS/hwdef/f103-RangeFinder/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/f103-RangeFinder/hwdef.dat
index 1ad383b269..cf8e275984 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/f103-RangeFinder/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/f103-RangeFinder/hwdef.dat
@@ -11,3 +11,6 @@ define HAL_PERIPH_ENABLE_RANGEFINDER
 define RANGEFINDER_MAX_INSTANCES 1
 
 define HAL_SERIAL3_PROTOCOL SerialProtocol_Rangefinder
+
+# we're too low on flash with old compler for bootloader
+define HAL_NO_ROMFS_SUPPORT