diff --git a/board/mbx8xx/flash.c b/board/mbx8xx/flash.c
index e1aa47b..a491f7b 100644
--- a/board/mbx8xx/flash.c
+++ b/board/mbx8xx/flash.c
@@ -79,7 +79,7 @@
     /* monitor protection ON by default */
     flash_protect(FLAG_PROTECT_SET,
 		  CFG_MONITOR_BASE,
-		  CFG_MONITOR_BASE+CFG_MONITOR_LEN-1,
+		  CFG_MONITOR_BASE+monitor_flash_len-1,
 		  &flash_info[0]);
 #endif