diff --git a/include/fmt/xchar.h b/include/fmt/xchar.h
index 463dbd9fb4fcc..5b076054d6e42 100644
--- a/include/fmt/xchar.h
+++ b/include/fmt/xchar.h
@@ -235,6 +235,7 @@ inline auto vformat_to(Char (&out)[Size], const Locale& loc,
                        const S& format_str,
                        typename detail::vformat_args<Char>::type args)
     -> format_to_result<Char*> {
+  using traits = detail::fixed_buffer_traits;
   auto&& buf = detail::iterator_buffer<Char*, Char, traits>(out, Size);
   vformat_to(buf, detail::to_string_view(format_str), args,
              detail::locale_ref(loc));