diff --git a/include/fmt/core.h b/include/fmt/core.h
index fef420d2..27bce7a9 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -394,22 +394,23 @@ template <typename T, typename Char>
 struct is_named_arg<named_arg<T, Char>> : std::true_type {};
 
 enum type {
-  NONE, NAMED_ARG,
+  none_type, name_arg_type,
   // Integer types should go first,
-  INT, UINT, LONG_LONG, ULONG_LONG, BOOL, CHAR, LAST_INTEGER_TYPE = CHAR,
+  int_type, uint_type, long_long_type, ulong_long_type, bool_type, char_type,
+  last_integer_type = char_type,
   // followed by floating-point types.
-  DOUBLE, LONG_DOUBLE, LAST_NUMERIC_TYPE = LONG_DOUBLE,
-  CSTRING, STRING, POINTER, CUSTOM
+  double_type, long_double_type, last_numeric_type = long_double_type,
+  cstring_type, string_type, pointer_type, custom_type
 };
 
 FMT_CONSTEXPR bool is_integral(type t) {
-  FMT_ASSERT(t != internal::NAMED_ARG, "invalid argument type");
-  return t > internal::NONE && t <= internal::LAST_INTEGER_TYPE;
+  FMT_ASSERT(t != internal::name_arg_type, "invalid argument type");
+  return t > internal::none_type && t <= internal::last_integer_type;
 }
 
 FMT_CONSTEXPR bool is_arithmetic(type t) {
-  FMT_ASSERT(t != internal::NAMED_ARG, "invalid argument type");
-  return t > internal::NONE && t <= internal::LAST_NUMERIC_TYPE;
+  FMT_ASSERT(t != internal::name_arg_type, "invalid argument type");
+  return t > internal::none_type && t <= internal::last_numeric_type;
 }
 
 template <typename T, bool ENABLE = true>
@@ -519,61 +520,63 @@ template <typename Context, typename T>
 FMT_CONSTEXPR basic_arg<Context> make_arg(const T &value);
 
 #define FMT_MAKE_VALUE(TAG, ArgType, ValueType) \
-  template <typename C, typename char_type = typename C::char_type> \
+  template <typename C, typename Char = typename C::char_type> \
   FMT_CONSTEXPR typed_value<C, TAG> make_value(ArgType val) { \
     return static_cast<ValueType>(val); \
   }
 
-FMT_MAKE_VALUE(BOOL, bool, int)
-FMT_MAKE_VALUE(INT, short, int)
-FMT_MAKE_VALUE(UINT, unsigned short, unsigned)
-FMT_MAKE_VALUE(INT, int, int)
-FMT_MAKE_VALUE(UINT, unsigned, unsigned)
+FMT_MAKE_VALUE(bool_type, bool, int)
+FMT_MAKE_VALUE(int_type, short, int)
+FMT_MAKE_VALUE(uint_type, unsigned short, unsigned)
+FMT_MAKE_VALUE(int_type, int, int)
+FMT_MAKE_VALUE(uint_type, unsigned, unsigned)
 
 // To minimize the number of types we need to deal with, long is translated
 // either to int or to long long depending on its size.
 typedef std::conditional<sizeof(long) == sizeof(int), int, long long>::type
         long_type;
-FMT_MAKE_VALUE((sizeof(long) == sizeof(int) ? INT : LONG_LONG), long, long_type)
+FMT_MAKE_VALUE(
+    (sizeof(long) == sizeof(int) ? int_type : long_long_type), long, long_type)
 typedef std::conditional<sizeof(unsigned long) == sizeof(unsigned),
                          unsigned, unsigned long long>::type ulong_type;
-FMT_MAKE_VALUE((sizeof(unsigned long) == sizeof(unsigned) ? UINT : ULONG_LONG),
+FMT_MAKE_VALUE(
+    (sizeof(unsigned long) == sizeof(unsigned) ? uint_type : ulong_long_type),
     unsigned long, ulong_type)
 
-FMT_MAKE_VALUE(LONG_LONG, long long, long long)
-FMT_MAKE_VALUE(ULONG_LONG, unsigned long long, unsigned long long)
-FMT_MAKE_VALUE(INT, signed char, int)
-FMT_MAKE_VALUE(UINT, unsigned char, unsigned)
-FMT_MAKE_VALUE(CHAR, char, int)
+FMT_MAKE_VALUE(long_long_type, long long, long long)
+FMT_MAKE_VALUE(ulong_long_type, unsigned long long, unsigned long long)
+FMT_MAKE_VALUE(int_type, signed char, int)
+FMT_MAKE_VALUE(uint_type, unsigned char, unsigned)
+FMT_MAKE_VALUE(char_type, char, int)
 
 #if !defined(_MSC_VER) || defined(_NATIVE_WCHAR_T_DEFINED)
 template <typename C>
-inline typed_value<C, CHAR> make_value(wchar_t val) {
+inline typed_value<C, char_type> make_value(wchar_t val) {
   require_wchar<typename C::char_type>();
   return static_cast<int>(val);
 }
 #endif
 
-FMT_MAKE_VALUE(DOUBLE, float, double)
-FMT_MAKE_VALUE(DOUBLE, double, double)
-FMT_MAKE_VALUE(LONG_DOUBLE, long double, long double)
+FMT_MAKE_VALUE(double_type, float, double)
+FMT_MAKE_VALUE(double_type, double, double)
+FMT_MAKE_VALUE(long_double_type, long double, long double)
 
 // Formatting of wide strings into a narrow buffer and multibyte strings
 // into a wide buffer is disallowed (https://github.com/fmtlib/fmt/pull/606).
-FMT_MAKE_VALUE(CSTRING, char_type*, const char_type*)
-FMT_MAKE_VALUE(CSTRING, const char_type*, const char_type*)
+FMT_MAKE_VALUE(cstring_type, Char*, const Char*)
+FMT_MAKE_VALUE(cstring_type, const Char*, const Char*)
 
-FMT_MAKE_VALUE(CSTRING, signed char*, const signed char*)
-FMT_MAKE_VALUE(CSTRING, const signed char*, const signed char*)
-FMT_MAKE_VALUE(CSTRING, unsigned char*, const unsigned char*)
-FMT_MAKE_VALUE(CSTRING, const unsigned char*, const unsigned char*)
-FMT_MAKE_VALUE(STRING, basic_string_view<char_type>,
-               basic_string_view<char_type>)
-FMT_MAKE_VALUE(STRING, const std::basic_string<char_type>&,
-               basic_string_view<char_type>)
-FMT_MAKE_VALUE(POINTER, void*, const void*)
-FMT_MAKE_VALUE(POINTER, const void*, const void*)
-FMT_MAKE_VALUE(POINTER, std::nullptr_t, const void*)
+FMT_MAKE_VALUE(cstring_type, signed char*, const signed char*)
+FMT_MAKE_VALUE(cstring_type, const signed char*, const signed char*)
+FMT_MAKE_VALUE(cstring_type, unsigned char*, const unsigned char*)
+FMT_MAKE_VALUE(cstring_type, const unsigned char*, const unsigned char*)
+FMT_MAKE_VALUE(string_type, basic_string_view<Char>,
+               basic_string_view<Char>)
+FMT_MAKE_VALUE(string_type, const std::basic_string<Char>&,
+               basic_string_view<Char>)
+FMT_MAKE_VALUE(pointer_type, void*, const void*)
+FMT_MAKE_VALUE(pointer_type, const void*, const void*)
+FMT_MAKE_VALUE(pointer_type, std::nullptr_t, const void*)
 
 // Formatting of arbitrary pointers is disallowed. If you want to output a
 // pointer cast it to "void *" or "const void *". In particular, this forbids
@@ -587,16 +590,16 @@ void make_value(const T *p) {
 template <typename C, typename T>
 inline typename std::enable_if<
     convert_to_int<T>::value && std::is_enum<T>::value,
-    typed_value<C, INT>>::type
+    typed_value<C, int_type>>::type
   make_value(const T &val) { return static_cast<int>(val); }
 
 template <typename C, typename T>
 inline typename std::enable_if<
-    !convert_to_int<T>::value, typed_value<C, CUSTOM>>::type
+    !convert_to_int<T>::value, typed_value<C, custom_type>>::type
   make_value(const T &val) { return val; }
 
 template <typename C, typename T>
-typed_value<C, NAMED_ARG>
+typed_value<C, name_arg_type>
     make_value(const named_arg<T, typename C::char_type> &val) {
   basic_arg<C> arg = make_arg<C>(val.value);
   std::memcpy(val.data, &arg, sizeof(arg));
@@ -641,17 +644,17 @@ class basic_arg {
     internal::custom_value<Context> custom_;
   };
 
-  FMT_CONSTEXPR basic_arg() : type_(internal::NONE) {}
+  FMT_CONSTEXPR basic_arg() : type_(internal::none_type) {}
 
   explicit operator bool() const FMT_NOEXCEPT {
-    return type_ != internal::NONE;
+    return type_ != internal::none_type;
   }
 
   internal::type type() const { return type_; }
 
   bool is_integral() const { return internal::is_integral(type_); }
   bool is_arithmetic() const { return internal::is_arithmetic(type_); }
-  bool is_pointer() const { return type_ == internal::POINTER; }
+  bool is_pointer() const { return type_ == internal::pointer_type; }
 };
 
 // Parsing context consisting of a format string range being parsed and an
@@ -982,7 +985,7 @@ class basic_format_args {
     if (index > internal::MAX_PACKED_ARGS)
       return arg;
     arg.type_ = type(index);
-    if (arg.type_ == internal::NONE)
+    if (arg.type_ == internal::none_type)
       return arg;
     internal::value<Context> &val = arg.value_;
     val = values_[index];
@@ -1001,7 +1004,7 @@ class basic_format_args {
   /** Returns the argument at specified index. */
   format_arg operator[](size_type index) const {
     format_arg arg = get(index);
-    return arg.type_ == internal::NAMED_ARG ?
+    return arg.type_ == internal::name_arg_type ?
           arg.value_.as_named_arg().template deserialize<Context>() : arg;
   }
 
diff --git a/include/fmt/format.h b/include/fmt/format.h
index e1c3e155..c6120fa7 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -1006,35 +1006,35 @@ FMT_CONSTEXPR typename std::result_of<Visitor(int)>::type
     visit(Visitor &&vis, basic_arg<Context> arg) {
   typedef typename Context::char_type char_type;
   switch (arg.type_) {
-  case internal::NONE:
+  case internal::none_type:
     return vis(monostate());
-  case internal::NAMED_ARG:
+  case internal::name_arg_type:
     FMT_ASSERT(false, "invalid argument type");
     break;
-  case internal::INT:
+  case internal::int_type:
     return vis(arg.value_.int_value);
-  case internal::UINT:
+  case internal::uint_type:
     return vis(arg.value_.uint_value);
-  case internal::LONG_LONG:
+  case internal::long_long_type:
     return vis(arg.value_.long_long_value);
-  case internal::ULONG_LONG:
+  case internal::ulong_long_type:
     return vis(arg.value_.ulong_long_value);
-  case internal::BOOL:
+  case internal::bool_type:
     return vis(arg.value_.int_value != 0);
-  case internal::CHAR:
+  case internal::char_type:
     return vis(static_cast<char_type>(arg.value_.int_value));
-  case internal::DOUBLE:
+  case internal::double_type:
     return vis(arg.value_.double_value);
-  case internal::LONG_DOUBLE:
+  case internal::long_double_type:
     return vis(arg.value_.long_double_value);
-  case internal::CSTRING:
+  case internal::cstring_type:
     return vis(arg.value_.string.value);
-  case internal::STRING:
+  case internal::string_type:
     return vis(basic_string_view<char_type>(
                  arg.value_.string.value, arg.value_.string.size));
-  case internal::POINTER:
+  case internal::pointer_type:
     return vis(arg.value_.pointer);
-  case internal::CUSTOM:
+  case internal::custom_type:
     return vis(typename basic_arg<Context>::handle(arg.value_.custom));
   }
   return typename std::result_of<Visitor(int)>::type();
@@ -1293,14 +1293,14 @@ void arg_map<Context>::init(const basic_format_args<Context> &args) {
   if (map_)
     return;
   map_ = new entry[args.max_size()];
-  bool use_values = args.type(MAX_PACKED_ARGS - 1) == internal::NONE;
+  bool use_values = args.type(MAX_PACKED_ARGS - 1) == internal::none_type;
   if (use_values) {
     for (unsigned i = 0;/*nothing*/; ++i) {
       internal::type arg_type = args.type(i);
       switch (arg_type) {
-        case internal::NONE:
+        case internal::none_type:
           return;
-        case internal::NAMED_ARG:
+        case internal::name_arg_type:
           push_back(args.values_[i]);
           break;
         default:
@@ -1310,14 +1310,14 @@ void arg_map<Context>::init(const basic_format_args<Context> &args) {
     return;
   }
   for (unsigned i = 0; i != MAX_PACKED_ARGS; ++i) {
-    if (args.type(i) == internal::NAMED_ARG)
+    if (args.type(i) == internal::name_arg_type)
       push_back(args.args_[i].value_);
   }
   for (unsigned i = MAX_PACKED_ARGS; ; ++i) {
     switch (args.args_[i].type_) {
-      case internal::NONE:
+      case internal::none_type:
         return;
-      case internal::NAMED_ARG:
+      case internal::name_arg_type:
         push_back(args.args_[i].value_);
         break;
       default:
@@ -1614,7 +1614,7 @@ class specs_checker : public Handler {
   }
 
   FMT_CONSTEXPR void end_precision() {
-    if (is_integral(arg_type_) || arg_type_ == POINTER)
+    if (is_integral(arg_type_) || arg_type_ == pointer_type)
       this->on_error("precision not allowed for this argument type");
   }
 
@@ -1626,8 +1626,8 @@ class specs_checker : public Handler {
 
   FMT_CONSTEXPR void check_sign() {
     require_numeric_argument();
-    if (is_integral(arg_type_) && arg_type_ != INT && arg_type_ != LONG_LONG &&
-        arg_type_ != CHAR) {
+    if (is_integral(arg_type_) && arg_type_ != int_type &&
+        arg_type_ != long_long_type && arg_type_ != char_type) {
       this->on_error("format specifier requires signed argument");
     }
   }
@@ -2062,7 +2062,7 @@ FMT_CONSTEXPR bool check_format_string(
 // because of a bug in MSVC.
 template <typename Context, typename T>
 struct format_type :
-  std::integral_constant<bool, get_type<Context, T>::value != CUSTOM> {};
+  std::integral_constant<bool, get_type<Context, T>::value != custom_type> {};
 
 // Specifies whether to format enums.
 template <typename T, typename Enable = void>
@@ -2942,38 +2942,38 @@ struct formatter<
     auto type_spec = specs_.type();
     auto eh = ctx.error_handler();
     switch (type) {
-    case internal::NONE:
-    case internal::NAMED_ARG:
+    case internal::none_type:
+    case internal::name_arg_type:
       FMT_ASSERT(false, "invalid argument type");
       break;
-    case internal::INT:
-    case internal::UINT:
-    case internal::LONG_LONG:
-    case internal::ULONG_LONG:
-    case internal::BOOL:
+    case internal::int_type:
+    case internal::uint_type:
+    case internal::long_long_type:
+    case internal::ulong_long_type:
+    case internal::bool_type:
       handle_int_type_spec(
             type_spec, internal::int_type_checker<decltype(eh)>(eh));
       break;
-    case internal::CHAR:
+    case internal::char_type:
       handle_char_specs(specs_, internal::char_specs_checker<decltype(eh)>(
                           type_spec, eh));
       break;
-    case internal::DOUBLE:
-    case internal::LONG_DOUBLE:
+    case internal::double_type:
+    case internal::long_double_type:
       handle_float_type_spec(
             type_spec, internal::float_type_checker<decltype(eh)>(eh));
       break;
-    case internal::CSTRING:
+    case internal::cstring_type:
       internal::handle_cstring_type_spec(
             type_spec, internal::cstring_type_checker<decltype(eh)>(eh));
       break;
-    case internal::STRING:
+    case internal::string_type:
       internal::check_string_type_spec(type_spec, eh);
       break;
-    case internal::POINTER:
+    case internal::pointer_type:
       internal::check_pointer_type_spec(type_spec, eh);
       break;
-    case internal::CUSTOM:
+    case internal::custom_type:
       // Custom format specifiers should be checked in parse functions of
       // formatter specializations.
       break;
@@ -3080,7 +3080,7 @@ typename basic_context<Range, Char>::format_arg
   basic_context<Range, Char>::get_arg(basic_string_view<char_type> name) {
   map_.init(this->args());
   format_arg arg = map_.find(name);
-  if (arg.type() == internal::NONE)
+  if (arg.type() == internal::none_type)
     this->on_error("argument not found");
   return arg;
 }
diff --git a/test/format-test.cc b/test/format-test.cc
index b7093e3d..67f6da35 100644
--- a/test/format-test.cc
+++ b/test/format-test.cc
@@ -1811,7 +1811,7 @@ TEST(FormatTest, ConstexprDynamicSpecsHandler) {
 
 FMT_CONSTEXPR test_format_specs_handler check_specs(const char *s) {
   fmt::internal::specs_checker<test_format_specs_handler>
-      checker(test_format_specs_handler(), fmt::internal::DOUBLE);
+      checker(test_format_specs_handler(), fmt::internal::double_type);
   parse_format_specs(s, checker);
   return checker;
 }