--- old/make/autoconf/build-aux/autoconf-config.sub	2018-01-23 23:09:29.284598800 +0900
+++ new/make/autoconf/build-aux/autoconf-config.sub	2018-01-23 23:09:28.765617200 +0900
@@ -1284,7 +1284,7 @@
 	      | -os2* | -vos* | -palmos* | -uclinux* | -nucleus* \
 	      | -morphos* | -superux* | -rtmk* | -rtmk-nova* | -windiss* \
 	      | -powermax* | -dnix* | -nx6 | -nx7 | -sei* | -dragonfly* \
-	      | -skyos* | -haiku* | -rdos* | -toppers* | -drops*)
+	      | -skyos* | -haiku* | -rdos* | -toppers* | -drops* | -wsl*)
 	# Remember, each alternative MUST END IN *, to match a version number.
 		;;
 	-qnx*)