diff --git a/[refs] b/[refs]
index 24d319078bec..817d4868cd10 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 24cc7b8a2a48a5707637e918a51ea547efe24892
+refs/heads/master: e1d0fe3cddf2306e3ac32569aa152f1909c9b46e
diff --git a/trunk/drivers/mtd/mtdconcat.c b/trunk/drivers/mtd/mtdconcat.c
index 7e075621bbf4..4567bc373780 100644
--- a/trunk/drivers/mtd/mtdconcat.c
+++ b/trunk/drivers/mtd/mtdconcat.c
@@ -540,10 +540,12 @@ static int concat_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 		else
 			size = len;
 
-		err = subdev->lock(subdev, ofs, size);
-
-		if (err)
-			break;
+		if (subdev->lock) {
+			err = subdev->lock(subdev, ofs, size);
+			if (err)
+				break;
+		} else
+			err = -EOPNOTSUPP;
 
 		len -= size;
 		if (len == 0)
@@ -578,10 +580,12 @@ static int concat_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 		else
 			size = len;
 
-		err = subdev->unlock(subdev, ofs, size);
-
-		if (err)
-			break;
+		if (subdev->unlock) {
+			err = subdev->unlock(subdev, ofs, size);
+			if (err)
+				break;
+		} else
+			err = -EOPNOTSUPP;
 
 		len -= size;
 		if (len == 0)