diff --git a/source/fatfs/ffconf.h b/source/fatfs/ffconf.h
index ce860e4..e1f75e6 100644
--- a/source/fatfs/ffconf.h
+++ b/source/fatfs/ffconf.h
@@ -229,7 +229,7 @@
 /  These options have no effect at read-only configuration (_FS_READONLY = 1). */
 
 
-#define	_FS_LOCK	0
+#define	_FS_LOCK	8
 /* The option _FS_LOCK switches file lock function to control duplicated file open
 /  and illegal operation to open objects. This option must be 0 when _FS_READONLY
 /  is 1.