diff --git a/LICENSE.txt b/LICENSE.txt
index 8da9c3d..3e937de 100644
--- a/LICENSE.txt
+++ b/LICENSE.txt
@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2020 Kenta Kubo
+Copyright (c) 2020-2023 Kenta Kubo
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal