diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index 7d377c9a5e35a..6627b26a800ca 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -357,7 +357,7 @@ static int parse_mount_options(struct ceph_mount_options **pfsopt,
 	}
 	err = -EINVAL;
 	dev_name_end--;		/* back up to ':' separator */
-	if (*dev_name_end != ':') {
+	if (dev_name_end < dev_name || *dev_name_end != ':') {
 		pr_err("device name is missing path (no : separator in %s)\n",
 				dev_name);
 		goto out;