diff --git a/join.c b/join.c
index cdfdb1f..2522404 100644
--- a/join.c
+++ b/join.c
@@ -1,3 +1,4 @@
+/* See LICENSE file for copyright and license details. */
 #include <ctype.h>
 #include <stdint.h>
 #include <stdio.h>