Get default of TEST_SSH_UTF8 from environment.
diff --git a/configure.ac b/configure.ac
index 5958252..eb9f45d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1777,7 +1777,7 @@
 AC_CHECK_FUNCS([mblen mbtowc nl_langinfo wcwidth])
 CFLAGS="$saved_CFLAGS"
 
-TEST_SSH_UTF8=yes
+TEST_SSH_UTF8=${TEST_SSH_UTF8:=yes}
 AC_MSG_CHECKING([for utf8 locale support])
 AC_RUN_IFELSE(
 	[AC_LANG_PROGRAM([[