diff --git a/main.c b/main.c
index 3fe03c2..e4fe01f 100644
--- a/main.c
+++ b/main.c
@@ -1,3 +1,20 @@
+/*
+ * Copyright 2018 Google LLC
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
 #include <linux/hrtimer.h>
 #include <linux/init.h>
 #include <linux/kernel.h>