diff --git a/board/bmw/flash.c b/board/bmw/flash.c
index 6a7649f..be62274 100644
--- a/board/bmw/flash.c
+++ b/board/bmw/flash.c
@@ -219,7 +219,7 @@
 #if CFG_MONITOR_BASE >= CFG_FLASH_BASE
     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