diff --git a/include/fmt/base.h b/include/fmt/base.h
index 0dc6ce06..bf78f713 100644
--- a/include/fmt/base.h
+++ b/include/fmt/base.h
@@ -2125,6 +2125,7 @@ template <typename T, typename Char> struct type_is_unformattable_for;
 template <typename Char> struct string_value {
   const Char* data;
   size_t size;
+  auto str() const -> basic_string_view<Char> { return {data, size}; }
 };
 
 template <typename Char> struct named_arg_value {
@@ -2542,10 +2543,8 @@ template <typename Context> class basic_format_arg {
     case detail::type::double_type:      return vis(value_.double_value);
     case detail::type::long_double_type: return vis(value_.long_double_value);
     case detail::type::cstring_type:     return vis(value_.string.data);
-    case detail::type::string_type:
-      using sv = basic_string_view<char_type>;
-      return vis(sv(value_.string.data, value_.string.size));
-    case detail::type::pointer_type: return vis(value_.pointer);
+    case detail::type::string_type:      return vis(value_.string.str());
+    case detail::type::pointer_type:     return vis(value_.pointer);
     case detail::type::custom_type:
       return vis(typename basic_format_arg<Context>::handle(value_.custom));
     }
diff --git a/include/fmt/format.h b/include/fmt/format.h
index a6cafc01..ad66aeb2 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -534,11 +534,6 @@ FMT_INLINE void assume(bool condition) {
 #endif
 }
 
-// An approximation of iterator_t for pre-C++20 systems.
-template <typename T>
-using iterator_t = decltype(std::begin(std::declval<T&>()));
-template <typename T> using sentinel_t = decltype(std::end(std::declval<T&>()));
-
 // A workaround for std::string not having mutable data() until C++17.
 template <typename Char>
 inline auto get_data(std::basic_string<Char>& s) -> Char* {
diff --git a/include/fmt/xchar.h b/include/fmt/xchar.h
index 3d928a45..51c11255 100644
--- a/include/fmt/xchar.h
+++ b/include/fmt/xchar.h
@@ -144,7 +144,7 @@ auto join(It begin, Sentinel end, wstring_view sep)
 
 template <typename Range>
 auto join(Range&& range, wstring_view sep)
-    -> join_view<detail::iterator_t<Range>, detail::sentinel_t<Range>,
+    -> join_view<decltype(std::begin(range)), decltype(std::end(range)),
                  wchar_t> {
   return join(std::begin(range), std::end(range), sep);
 }