diff --git a/bin/sync/sync.c b/bin/sync/sync.c
--- a/bin/sync/sync.c
+++ b/bin/sync/sync.c
@@ -1,4 +1,6 @@
 /*-
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
  * Copyright (c) 1987, 1993
  *	The Regents of the University of California.  All rights reserved.
  *