diff --git a/include/fmt/format.h b/include/fmt/format.h
index c57c0e6e..57fc059c 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -3333,11 +3333,9 @@ inline namespace literals {
   \endrst
  */
 #  if FMT_USE_NONTYPE_TEMPLATE_PARAMETERS
-template <detail_exported::fixed_string Str>
-constexpr auto operator""_a()
-    -> detail::udl_arg<remove_cvref_t<decltype(Str.data[0])>,
-                       sizeof(Str.data) / sizeof(decltype(Str.data[0])), Str> {
-  return {};
+template <detail_exported::fixed_string Str> constexpr auto operator""_a() {
+  using char_t = remove_cvref_t<decltype(Str.data[0])>;
+  return detail::udl_arg<char_t, sizeof(Str.data) / sizeof(char_t), Str>();
 }
 #  else
 constexpr auto operator"" _a(const char* s, size_t) -> detail::udl_arg<char> {