diff --git a/include/fmt/xchar.h b/include/fmt/xchar.h
index 625ec36922e9b..2bf8c27649de1 100644
--- a/include/fmt/xchar.h
+++ b/include/fmt/xchar.h
@@ -70,7 +70,7 @@ constexpr format_arg_store<wformat_context, T...> make_wformat_args(
 
 inline namespace literals {
 #if FMT_USE_USER_DEFINED_LITERALS && !FMT_USE_NONTYPE_TEMPLATE_ARGS
-constexpr detail::udl_arg<wchar_t> operator"" _a(const wchar_t* s, size_t) {
+constexpr detail::udl_arg<wchar_t> operator""_a(const wchar_t* s, size_t) {
   return {s};
 }
 #endif