diff --git a/include/fmt/color.h b/include/fmt/color.h
index b29ab082..5c9b0491 100644
--- a/include/fmt/color.h
+++ b/include/fmt/color.h
@@ -556,7 +556,7 @@ std::basic_string<Char> vformat(
 }
 }  // namespace internal
 
-template <typename S, typename Char = typename internal::char_t<S>::type>
+template <typename S, typename Char = char_t<S> >
 void vprint(std::FILE* f, const text_style& ts, const S& format,
             basic_format_args<typename buffer_context<Char>::type> args) {
   bool has_style = false;
@@ -587,13 +587,12 @@ void vprint(std::FILE* f, const text_style& ts, const S& format,
     fmt::print(fmt::emphasis::bold | fg(fmt::color::red),
                "Elapsed time: {0:.2f} seconds", 1.23);
  */
-template <typename String, typename... Args,
-          FMT_ENABLE_IF(internal::is_string<String>::value)>
-void print(std::FILE* f, const text_style& ts, const String& format_str,
+template <typename S, typename... Args,
+          FMT_ENABLE_IF(internal::is_string<S>::value)>
+void print(std::FILE* f, const text_style& ts, const S& format_str,
            const Args&... args) {
   internal::check_format_string<Args...>(format_str);
-  typedef typename internal::char_t<String>::type char_t;
-  typedef typename buffer_context<char_t>::type context_t;
+  typedef typename buffer_context<char_t<S> >::type context_t;
   format_arg_store<context_t, Args...> as{args...};
   vprint(f, ts, format_str, basic_format_args<context_t>(as));
 }
@@ -605,14 +604,13 @@ void print(std::FILE* f, const text_style& ts, const String& format_str,
     fmt::print(fmt::emphasis::bold | fg(fmt::color::red),
                "Elapsed time: {0:.2f} seconds", 1.23);
  */
-template <typename String, typename... Args,
-          FMT_ENABLE_IF(internal::is_string<String>::value)>
-void print(const text_style& ts, const String& format_str,
-           const Args&... args) {
+template <typename S, typename... Args,
+          FMT_ENABLE_IF(internal::is_string<S>::value)>
+void print(const text_style& ts, const S& format_str, const Args&... args) {
   return print(stdout, ts, format_str, args...);
 }
 
-template <typename S, typename Char = FMT_CHAR(S)>
+template <typename S, typename Char = char_t<S> >
 inline std::basic_string<Char> vformat(
     const text_style& ts, const S& format_str,
     basic_format_args<typename buffer_context<Char>::type> args) {
@@ -631,10 +629,9 @@ inline std::basic_string<Char> vformat(
                                       "The answer is {}", 42);
   \endrst
 */
-template <typename S, typename... Args>
-inline std::basic_string<FMT_CHAR(S)> format(const text_style& ts,
-                                             const S& format_str,
-                                             const Args&... args) {
+template <typename S, typename... Args, typename Char = char_t<S> >
+inline std::basic_string<Char> format(const text_style& ts, const S& format_str,
+                                      const Args&... args) {
   return internal::vformat(ts, to_string_view(format_str),
                            {internal::make_args_checked(format_str, args...)});
 }
diff --git a/include/fmt/core.h b/include/fmt/core.h
index e9cea570..3298b05f 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -617,7 +617,7 @@ struct is_string
 template <> struct is_string<std::FILE*>;
 template <> struct is_string<const std::FILE*>;
 
-template <typename S> struct char_t {
+template <typename S> struct char_t_impl {
   typedef decltype(to_string_view(std::declval<S>())) result;
   typedef typename result::char_type type;
 };
@@ -883,7 +883,7 @@ FMT_CONSTEXPR11 init<C, basic_string_view<typename C::char_type>, string_type>
 make_value(const S& val) {
   // Handle adapted strings.
   static_assert(std::is_same<typename C::char_type,
-                             typename internal::char_t<S>::type>::value,
+                             typename internal::char_t_impl<S>::type>::value,
                 "mismatch between char-types of context and argument");
   return to_string_view(val);
 }
@@ -1311,8 +1311,7 @@ struct wformat_args : basic_format_args<wformat_context> {
 };
 
 /** String's character type. */
-template <typename S> using char_t = typename internal::char_t<S>::type;
-#define FMT_CHAR(S) fmt::char_t<S>
+template <typename S> using char_t = typename internal::char_t_impl<S>::type;
 
 namespace internal {
 template <typename Context>
@@ -1353,8 +1352,8 @@ template <typename... Args, typename S,
 void check_format_string(S);
 
 template <typename S, typename... Args,
-          FMT_ENABLE_IF(internal::is_string<S>::value)>
-inline format_arg_store<typename buffer_context<FMT_CHAR(S)>::type, Args...>
+          typename Char = enable_if_t<internal::is_string<S>::value, char_t<S>>>
+inline format_arg_store<typename buffer_context<Char>::type, Args...>
 make_args_checked(const S& format_str, const Args&... args) {
   internal::check_format_string<Args...>(format_str);
   return {args...};
@@ -1386,8 +1385,8 @@ typename buffer_context<Char>::type::iterator vformat_to(
     fmt::print("Elapsed time: {s:.2f} seconds", fmt::arg("s", 1.23));
   \endrst
  */
-template <typename S, typename T>
-inline internal::named_arg<T, FMT_CHAR(S)> arg(const S& name, const T& arg) {
+template <typename S, typename T, typename Char = char_t<S>>
+inline internal::named_arg<T, Char> arg(const S& name, const T& arg) {
   static_assert(internal::is_string<S>::value, "");
   return {name, arg};
 }
@@ -1404,13 +1403,23 @@ struct is_contiguous<std::basic_string<Char>> : std::true_type {};
 template <typename Char>
 struct is_contiguous<internal::buffer<Char>> : std::true_type {};
 
+template <typename OutputIt>
+struct is_contiguous_back_insert_iterator : std::false_type {};
+
+template <typename Container>
+struct is_contiguous_back_insert_iterator<std::back_insert_iterator<Container>>
+    : is_contiguous<Container> {};
+
 /** Formats a string and writes the output to ``out``. */
-template <typename Container, typename S>
-typename std::enable_if<is_contiguous<Container>::value,
-                        std::back_insert_iterator<Container>>::type
-vformat_to(std::back_insert_iterator<Container> out, const S& format_str,
-           basic_format_args<typename buffer_context<FMT_CHAR(S)>::type> args) {
-  internal::container_buffer<Container> buf(internal::get_container(out));
+template <typename OutputIt, typename S,
+          typename Char = enable_if_t<
+              is_contiguous_back_insert_iterator<OutputIt>::value, char_t<S>>>
+OutputIt vformat_to(
+    OutputIt out, const S& format_str,
+    basic_format_args<typename buffer_context<Char>::type> args) {
+  using container = typename std::remove_reference<decltype(
+      internal::get_container(out))>::type;
+  internal::container_buffer<container> buf((internal::get_container(out)));
   internal::vformat_to(buf, to_string_view(format_str), args);
   return out;
 }
@@ -1425,8 +1434,8 @@ inline std::back_insert_iterator<Container> format_to(
                     {internal::make_args_checked(format_str, args...)});
 }
 
-template <typename S, typename Char = FMT_CHAR(S),
-          FMT_ENABLE_IF(internal::is_string<S>::value)>
+template <typename S,
+          typename Char = enable_if_t<internal::is_string<S>::value, char_t<S>>>
 inline std::basic_string<Char> vformat(
     const S& format_str,
     basic_format_args<typename buffer_context<Char>::type> args) {
@@ -1443,11 +1452,12 @@ inline std::basic_string<Char> vformat(
     std::string message = fmt::format("The answer is {}", 42);
   \endrst
 */
-// Pass fmt::char_t as a default template parameter instead of using
-// std::basic_string<fmt::char_t<S>> to reduce the symbol size.
+// Pass char_t as a default template parameter instead of using
+// std::basic_string<char_t<S>> to reduce the symbol size.
 template <typename S, typename... Args,
           typename Char = enable_if_t<internal::is_string<S>::value, char_t<S>>>
-inline std::basic_string<Char> format(const S& format_str, const Args&... args) {
+inline std::basic_string<Char> format(const S& format_str,
+                                      const Args&... args) {
   return internal::vformat(to_string_view(format_str),
                            {internal::make_args_checked(format_str, args...)});
 }
diff --git a/include/fmt/format.h b/include/fmt/format.h
index 42846f90..c8ce2f39 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -1805,10 +1805,11 @@ struct string_view_metadata {
       : offset_(view.data() - primary_string.data()), size_(view.size()) {}
   FMT_CONSTEXPR string_view_metadata(std::size_t offset, std::size_t size)
       : offset_(offset), size_(size) {}
-  template <typename S, FMT_ENABLE_IF(internal::is_string<S>::value)>
-  FMT_CONSTEXPR basic_string_view<FMT_CHAR(S)> to_view(S&& str) const {
+  template <typename S, typename Char = enable_if_t<
+                            internal::is_string<S>::value, char_t<S>>>
+  FMT_CONSTEXPR basic_string_view<Char> to_view(S&& str) const {
     const auto view = to_string_view(str);
-    return basic_string_view<FMT_CHAR(S)>(view.data() + offset_, size_);
+    return basic_string_view<Char>(view.data() + offset_, size_);
   }
 
   std::size_t offset_;
@@ -3384,7 +3385,7 @@ typename buffer_context<Char>::type::iterator internal::vformat_to(
                                           args);
 }
 
-template <typename S, typename Char = FMT_CHAR(S),
+template <typename S, typename Char = char_t<S>,
           FMT_ENABLE_IF(internal::is_string<S>::value)>
 inline typename buffer_context<Char>::type::iterator vformat_to(
     internal::buffer<Char>& buf, const S& format_str,
@@ -3393,12 +3394,12 @@ inline typename buffer_context<Char>::type::iterator vformat_to(
 }
 
 template <typename S, typename... Args, std::size_t SIZE = inline_buffer_size,
-          typename Char = typename internal::char_t<S>::type>
+          typename Char = enable_if_t<internal::is_string<S>::value, char_t<S>>>
 inline typename buffer_context<Char>::type::iterator format_to(
     basic_memory_buffer<Char, SIZE>& buf, const S& format_str,
     const Args&... args) {
   internal::check_format_string<Args...>(format_str);
-  typedef typename buffer_context<Char>::type context;
+  using context = typename buffer_context<Char>::type;
   format_arg_store<context, Args...> as{args...};
   return internal::vformat_to(buf, to_string_view(format_str),
                               basic_format_args<context>(as));
@@ -3459,12 +3460,13 @@ struct format_args_t {
       type;
 };
 
-template <typename String, typename OutputIt, typename... Args,
-          FMT_ENABLE_IF(internal::is_output_iterator<OutputIt>::value)>
+template <typename S, typename OutputIt, typename... Args,
+          FMT_ENABLE_IF(internal::is_output_iterator<OutputIt>::value &&
+                        !is_contiguous_back_insert_iterator<OutputIt>::value)>
 inline OutputIt vformat_to(
-    OutputIt out, const String& format_str,
-    typename format_args_t<OutputIt, FMT_CHAR(String)>::type args) {
-  typedef output_range<OutputIt, FMT_CHAR(String)> range;
+    OutputIt out, const S& format_str,
+    typename format_args_t<OutputIt, char_t<S>>::type args) {
+  typedef output_range<OutputIt, char_t<S>> range;
   return vformat_to<arg_formatter<range>>(range(out),
                                           to_string_view(format_str), args);
 }
@@ -3481,13 +3483,13 @@ inline OutputIt vformat_to(
  \endrst
  */
 template <typename OutputIt, typename S, typename... Args>
-inline
-    typename std::enable_if<internal::is_string<S>::value &&
-                                internal::is_output_iterator<OutputIt>::value,
-                            OutputIt>::type
-    format_to(OutputIt out, const S& format_str, const Args&... args) {
+inline OutputIt format_to(OutputIt out, const S& format_str,
+                          const Args&... args) {
+  static_assert(internal::is_output_iterator<OutputIt>::value &&
+                    internal::is_string<S>::value,
+                "");
   internal::check_format_string<Args...>(format_str);
-  typedef typename format_context_t<OutputIt, FMT_CHAR(S)>::type context;
+  typedef typename format_context_t<OutputIt, char_t<S>>::type context;
   format_arg_store<context, Args...> as{args...};
   return vformat_to(out, to_string_view(format_str),
                     basic_format_args<context>(as));
@@ -3542,7 +3544,7 @@ inline format_to_n_result<OutputIt> format_to_n(OutputIt out, std::size_t n,
                                                 const S& format_str,
                                                 const Args&... args) {
   internal::check_format_string<Args...>(format_str);
-  typedef FMT_CHAR(S) Char;
+  using Char = char_t<S>;
   format_arg_store<typename format_to_n_context<OutputIt, Char>::type, Args...>
   as(args...);
   return vformat_to_n(out, n, to_string_view(format_str),
diff --git a/include/fmt/locale.h b/include/fmt/locale.h
index aeb35217..b6b4cf90 100644
--- a/include/fmt/locale.h
+++ b/include/fmt/locale.h
@@ -34,38 +34,39 @@ std::basic_string<Char> vformat(
 }
 }  // namespace internal
 
-template <typename S, typename Char = FMT_CHAR(S)>
+template <typename S, typename Char = char_t<S>>
 inline std::basic_string<Char> vformat(
     const std::locale& loc, const S& format_str,
     basic_format_args<typename buffer_context<Char>::type> args) {
   return internal::vformat(loc, to_string_view(format_str), args);
 }
 
-template <typename S, typename... Args>
-inline std::basic_string<FMT_CHAR(S)> format(const std::locale& loc,
-                                             const S& format_str,
-                                             const Args&... args) {
+template <typename S, typename... Args, typename Char = char_t<S>>
+inline std::basic_string<Char> format(const std::locale& loc,
+                                      const S& format_str,
+                                      const Args&... args) {
   return internal::vformat(loc, to_string_view(format_str),
                            {internal::make_args_checked(format_str, args...)});
 }
 
-template <typename String, typename OutputIt, typename... Args,
-          FMT_ENABLE_IF(internal::is_output_iterator<OutputIt>::value)>
-inline OutputIt vformat_to(
-    OutputIt out, const std::locale& loc, const String& format_str,
-    typename format_args_t<OutputIt, FMT_CHAR(String)>::type args) {
-  typedef output_range<OutputIt, FMT_CHAR(String)> range;
+template <typename S, typename OutputIt, typename... Args,
+          typename Char = enable_if_t<
+              internal::is_output_iterator<OutputIt>::value, char_t<S>>>
+inline OutputIt vformat_to(OutputIt out, const std::locale& loc,
+                           const S& format_str,
+                           typename format_args_t<OutputIt, Char>::type args) {
+  using range = output_range<OutputIt, Char>;
   return vformat_to<arg_formatter<range>>(
       range(out), to_string_view(format_str), args, internal::locale_ref(loc));
 }
 
 template <typename OutputIt, typename S, typename... Args,
-          FMT_ENABLE_IF(internal::is_string<S>::value&&
-                            internal::is_output_iterator<OutputIt>::value)>
+          FMT_ENABLE_IF(internal::is_output_iterator<OutputIt>::value&&
+                            internal::is_string<S>::value)>
 inline OutputIt format_to(OutputIt out, const std::locale& loc,
                           const S& format_str, const Args&... args) {
   internal::check_format_string<Args...>(format_str);
-  typedef typename format_context_t<OutputIt, FMT_CHAR(S)>::type context;
+  using context = typename format_context_t<OutputIt, char_t<S>>::type;
   format_arg_store<context, Args...> as{args...};
   return vformat_to(out, loc, to_string_view(format_str),
                     basic_format_args<context>(as));
diff --git a/include/fmt/ostream.h b/include/fmt/ostream.h
index 47d81a90..0399108f 100644
--- a/include/fmt/ostream.h
+++ b/include/fmt/ostream.h
@@ -120,13 +120,13 @@ struct convert_to_int<
 };
 
 template <typename Char>
-inline void vprint(
-    std::basic_ostream<Char>& os, basic_string_view<Char> format_str,
-    basic_format_args<typename buffer_context<Char>::type> args) {
+void vprint(std::basic_ostream<Char>& os, basic_string_view<Char> format_str,
+            basic_format_args<typename buffer_context<Char>::type> args) {
   basic_memory_buffer<Char> buffer;
   internal::vformat_to(buffer, format_str, args);
   internal::write(os, buffer);
 }
+
 /**
   \rst
   Prints formatted data to the stream *os*.
@@ -137,8 +137,8 @@ inline void vprint(
   \endrst
  */
 template <typename S, typename... Args,
-          FMT_ENABLE_IF(internal::is_string<S>::value)>
-inline void print(std::basic_ostream<FMT_CHAR(S)>& os, const S& format_str,
+          typename Char = enable_if_t<internal::is_string<S>::value, char_t<S>>>
+inline void print(std::basic_ostream<Char>& os, const S& format_str,
                   const Args&... args) {
   vprint(os, to_string_view(format_str),
          {internal::make_args_checked(format_str, args...)});
diff --git a/include/fmt/prepare.h b/include/fmt/prepare.h
index 7bfe73d4..7f4ff082 100644
--- a/include/fmt/prepare.h
+++ b/include/fmt/prepare.h
@@ -185,8 +185,8 @@ class format_preparation_handler : public internal::error_handler {
 template <typename Format, typename PreparedPartsProvider, typename... Args>
 class prepared_format {
  public:
-  typedef FMT_CHAR(Format) char_type;
-  typedef format_part<char_type> format_part_t;
+  using char_type = char_t<Format>;
+  using format_part_t = format_part<char_type>;
 
   prepared_format(Format f)
       : format_(std::move(f)), parts_provider_(to_string_view(format_)) {}
@@ -351,7 +351,7 @@ class prepared_format {
 
 template <typename Format> class compiletime_prepared_parts_type_provider {
  private:
-  typedef FMT_CHAR(Format) char_type;
+  using char_type = char_t<Format>;
 
   class count_handler {
    private:
@@ -649,7 +649,7 @@ class parts_container {
 // Delegate preparing to preparator, to take advantage of a partial
 // specialization.
 template <typename Format, typename... Args> struct preparator {
-  typedef parts_container<FMT_CHAR(Format)> container;
+  typedef parts_container<char_t<Format>> container;
   typedef typename basic_prepared_format<Format, container, Args...>::type
       prepared_format_type;
 
diff --git a/include/fmt/printf.h b/include/fmt/printf.h
index f879dc83..3dbf1fc0 100644
--- a/include/fmt/printf.h
+++ b/include/fmt/printf.h
@@ -608,7 +608,7 @@ inline format_arg_store<wprintf_context, Args...> make_wprintf_args(
   return {args...};
 }
 
-template <typename S, typename Char = FMT_CHAR(S)>
+template <typename S, typename Char = char_t<S>>
 inline std::basic_string<Char> vsprintf(
     const S& format,
     basic_format_args<
@@ -629,16 +629,14 @@ inline std::basic_string<Char> vsprintf(
   \endrst
 */
 template <typename S, typename... Args,
-          FMT_ENABLE_IF(internal::is_string<S>::value)>
-inline std::basic_string<FMT_CHAR(S)> sprintf(const S& format,
-                                              const Args&... args) {
-  typedef internal::buffer<FMT_CHAR(S)> buffer;
-  typedef typename basic_printf_context_t<buffer>::type context;
+          typename Char = enable_if_t<internal::is_string<S>::value, char_t<S>>>
+inline std::basic_string<Char> sprintf(const S& format, const Args&... args) {
+  using context = typename basic_printf_context_t<internal::buffer<Char>>::type;
   format_arg_store<context, Args...> as{args...};
   return vsprintf(to_string_view(format), basic_format_args<context>(as));
 }
 
-template <typename S, typename Char = FMT_CHAR(S)>
+template <typename S, typename Char = char_t<S>>
 inline int vfprintf(
     std::FILE* f, const S& format,
     basic_format_args<
@@ -662,15 +660,14 @@ inline int vfprintf(
   \endrst
  */
 template <typename S, typename... Args,
-          FMT_ENABLE_IF(internal::is_string<S>::value)>
+          typename Char = enable_if_t<internal::is_string<S>::value, char_t<S>>>
 inline int fprintf(std::FILE* f, const S& format, const Args&... args) {
-  typedef internal::buffer<FMT_CHAR(S)> buffer;
-  typedef typename basic_printf_context_t<buffer>::type context;
+  using context = typename basic_printf_context_t<internal::buffer<Char>>::type;
   format_arg_store<context, Args...> as{args...};
   return vfprintf(f, to_string_view(format), basic_format_args<context>(as));
 }
 
-template <typename S, typename Char = FMT_CHAR(S)>
+template <typename S, typename Char = char_t<S>>
 inline int vprintf(
     const S& format,
     basic_format_args<
@@ -692,13 +689,13 @@ template <typename S, typename... Args,
           FMT_ENABLE_IF(internal::is_string<S>::value)>
 inline int printf(const S& format_str, const Args&... args) {
   internal::check_format_string<Args...>(format_str);
-  typedef internal::buffer<FMT_CHAR(S)> buffer;
-  typedef typename basic_printf_context_t<buffer>::type context;
+  using buffer = internal::buffer<char_t<S>>;
+  using context = typename basic_printf_context_t<buffer>::type;
   format_arg_store<context, Args...> as{args...};
   return vprintf(to_string_view(format_str), basic_format_args<context>(as));
 }
 
-template <typename S, typename Char = FMT_CHAR(S)>
+template <typename S, typename Char = char_t<S>>
 inline int vfprintf(
     std::basic_ostream<Char>& os, const S& format,
     basic_format_args<
@@ -731,13 +728,11 @@ typename ArgFormatter::iterator vprintf(internal::buffer<Char>& out,
     fmt::fprintf(cerr, "Don't %s!", "panic");
   \endrst
  */
-template <typename S, typename... Args,
-          FMT_ENABLE_IF(internal::is_string<S>::value)>
-inline int fprintf(std::basic_ostream<FMT_CHAR(S)>& os, const S& format_str,
+template <typename S, typename... Args, typename Char = char_t<S>>
+inline int fprintf(std::basic_ostream<Char>& os, const S& format_str,
                    const Args&... args) {
   internal::check_format_string<Args...>(format_str);
-  typedef internal::buffer<FMT_CHAR(S)> buffer;
-  typedef typename basic_printf_context_t<buffer>::type context;
+  using context = typename basic_printf_context_t<internal::buffer<Char>>::type;
   format_arg_store<context, Args...> as{args...};
   return vfprintf(os, to_string_view(format_str),
                   basic_format_args<context>(as));