diff --git a/examples/common/default/footer.m4.html b/examples/common/default/footer.m4.html
index 7c383df..0f28c06 100644
--- a/examples/common/default/footer.m4.html
+++ b/examples/common/default/footer.m4.html
@@ -1,6 +1,6 @@
 <p class="copyright">Driven by
 <a href="http://www.gentei.org/~yuuji/software/s4/">s4</a>
-&copy;2015-2020 by
+&copy;2015-2021 by
 <a href="http://www.gentei.org/~yuuji/">yuuji</a>
 </body>
 </html>