diff --git a/rexbacklight.c b/rexbacklight.c
index d7c107a..6e46d15 100644
--- a/rexbacklight.c
+++ b/rexbacklight.c
@@ -1,3 +1,20 @@
+/**
+	rexbacklight
+	Copyright (C) 2018  rexy712
+
+	This program is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	This program is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>