diff --git a/libraries/AP_HAL_ChibiOS/hwdef/JHEMCU-H743HD/hwdef-bl.dat b/libraries/AP_HAL_ChibiOS/hwdef/JHEMCU-H743HD/hwdef-bl.dat
index e8a9001abcfaa8..307de8cf54f3b6 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/JHEMCU-H743HD/hwdef-bl.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/JHEMCU-H743HD/hwdef-bl.dat
@@ -14,7 +14,7 @@ OSCILLATOR_HZ 8000000
 
 MCU_CLOCKRATE_MHZ 480
 
-FLASH_SIZE_KB 2048
+FLASH_SIZE_KB 1024
 
 # bootloader starts at zero offset
 FLASH_RESERVE_START_KB 0