Update copyright notice
diff --git a/LICENSE.md b/LICENSE.md
index 77821f42..9f1d42e9 100644
--- a/LICENSE.md
+++ b/LICENSE.md
@@ -1,4 +1,4 @@
-Copyright 2019 mintsuki
+Copyright 2019-2020 mintsuki and contributors.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
