diff --git a/README.md b/README.md
index e94d6b3..da07c6a 100644
--- a/README.md
+++ b/README.md
@@ -555,7 +555,7 @@ See `vendor/README` in detail.
 
 The MIT License (MIT)
 
-Copyright (c) 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022 Yusuke Endoh (@mametter), @hirekoke
+Copyright (c) 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023 Yusuke Endoh (@mametter), @hirekoke
 
 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the
diff --git a/src/README.md.gen.rb b/src/README.md.gen.rb
index 6183d46..0339b8e 100644
--- a/src/README.md.gen.rb
+++ b/src/README.md.gen.rb
@@ -341,7 +341,7 @@
 
 The MIT License (MIT)
 
-Copyright (c) 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022 Yusuke Endoh (@mametter), @hirekoke
+Copyright (c) 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023 Yusuke Endoh (@mametter), @hirekoke
 
 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the