diff --git a/puzzles.but b/puzzles.but
index 18546ac..260ebbb 100644
--- a/puzzles.but
+++ b/puzzles.but
@@ -36,7 +36,7 @@
 
 This is a collection of small one-player puzzle games.
 
-\copyright This manual is copyright 2004-2021 Simon Tatham. All rights
+\copyright This manual is copyright 2004-2023 Simon Tatham. All rights
 reserved. You may distribute this documentation under the MIT licence.
 See \k{licence} for the licence text in full.