diff --git a/build-aux/m4/buildsys.m4 b/build-aux/m4/buildsys.m4
index 489fc9f..711f791 100644
--- a/build-aux/m4/buildsys.m4
+++ b/build-aux/m4/buildsys.m4
@@ -1,6 +1,6 @@
 dnl
 dnl Copyright (c) 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2016, 2017,
-dnl               2018, 2020
+dnl               2018, 2020, 2021
 dnl   Jonathan Schleifer <js@nil.im>
 dnl
 dnl https://fossil.nil.im/buildsys
diff --git a/buildsys.mk.in b/buildsys.mk.in
index fa6c443..3679df6 100644
--- a/buildsys.mk.in
+++ b/buildsys.mk.in
@@ -1,6 +1,6 @@
 #
 #  Copyright (c) 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016,
-#                2017, 2018, 2020
+#                2017, 2018, 2020, 2021
 #    Jonathan Schleifer <js@nil.im>
 #
 #  https://fossil.nil.im/buildsys