diff -ru rsync-3.1.3/config.sub rsync-3.1.3-port/config.sub
--- rsync-3.1.3/config.sub	2013-05-19 18:01:07.000000000 -0400
+++ rsync-3.1.3-port/config.sub	2020-05-01 20:10:00.171268526 -0400
@@ -1373,7 +1373,7 @@
 	      | -storm-chaos* | -tops10* | -tenex* | -tops20* | -its* \
 	      | -os2* | -vos* | -palmos* | -uclinux* | -nucleus* \
 	      | -morphos* | -superux* | -rtmk* | -rtmk-nova* | -windiss* \
-	      | -powermax* | -dnix* | -nx6 | -nx7 | -sei* | -dragonfly* \
+	      | -powermax* | -dnix* | -nx6 | -nx7 | -sei* | -dragonfly* | -serenity* \
 	      | -skyos* | -haiku* | -rdos* | -toppers* | -drops* | -es*)
 	# Remember, each alternative MUST END IN *, to match a version number.
 		;;