Fix for issue 8067
diff --git a/configure.in b/configure.in
index 4cc3491..b1450af 100644
--- a/configure.in
+++ b/configure.in
@@ -319,6 +319,8 @@
   # has no effect, don't bother defining them
   Darwin/@<:@6789@:>@.*)
     define_xopen_source=no;;
+  Darwin/1@<:@6789@:>@.*)
+    define_xopen_source=no;;
   # On AIX 4 and 5.1, mbstate_t is defined only when _XOPEN_SOURCE == 500 but
   # used in wcsnrtombs() and mbsnrtowcs() even if _XOPEN_SOURCE is not defined
   # or has another value. By not (re)defining it, the defaults come in place.