diff --git a/sbin/mount_ufs/mount_ufs.c b/sbin/mount_ufs/mount_ufs.c
index e37eadcb503c..ff8ab9dd716e 100644
--- a/sbin/mount_ufs/mount_ufs.c
+++ b/sbin/mount_ufs/mount_ufs.c
@@ -115,6 +115,7 @@ main(int argc, char **argv)
 	(void)rmslashes(dev, dev);
 
 	iov = NULL;
+	iovlen = 0;
 	build_iovec(&iov, &iovlen, "fstype", "ufs", -1);
 	build_iovec(&iov, &iovlen, "fspath", mntpath, -1);
 	build_iovec(&iov, &iovlen, "from", dev, -1);