diff --git a/include/fmt/chrono.h b/include/fmt/chrono.h
index 43daeeb4d390..74fc8485e44c 100644
--- a/include/fmt/chrono.h
+++ b/include/fmt/chrono.h
@@ -530,7 +530,7 @@ inline std::tm gmtime(
   return gmtime(std::chrono::system_clock::to_time_t(time_point));
 }
 
-FMT_BEGIN_DETAIL_NAMESPACE
+namespace detail {
 
 // DEPRECATED!
 template <typename Char>
@@ -1997,7 +1997,7 @@ struct chrono_formatter {
   }
 };
 
-FMT_END_DETAIL_NAMESPACE
+}  // namespace detail
 
 #if defined(__cpp_lib_chrono) && __cpp_lib_chrono >= 201907
 using weekday = std::chrono::weekday;
@@ -2142,8 +2142,8 @@ struct formatter<std::chrono::time_point<std::chrono::system_clock, Duration>,
           epoch - std::chrono::duration_cast<std::chrono::seconds>(epoch));
 
       if (subsecs.count() < 0) {
-        auto second = std::chrono::duration_cast<Duration>(
-            std::chrono::seconds(1));
+        auto second =
+            std::chrono::duration_cast<Duration>(std::chrono::seconds(1));
         if (epoch.count() < ((Duration::min)() + second).count())
           FMT_THROW(format_error("duration is too small"));
         subsecs += second;
diff --git a/include/fmt/color.h b/include/fmt/color.h
index d175448ab6af..8697e1ca0bad 100644
--- a/include/fmt/color.h
+++ b/include/fmt/color.h
@@ -203,7 +203,7 @@ struct rgb {
   uint8_t b;
 };
 
-FMT_BEGIN_DETAIL_NAMESPACE
+namespace detail {
 
 // color is a struct of either a rgb color or a terminal color.
 struct color_type {
@@ -225,8 +225,7 @@ struct color_type {
     uint32_t rgb_color;
   } value;
 };
-
-FMT_END_DETAIL_NAMESPACE
+}  // namespace detail
 
 /** A text style consisting of foreground and background colors and emphasis. */
 class text_style {
@@ -323,7 +322,7 @@ FMT_CONSTEXPR inline text_style operator|(emphasis lhs, emphasis rhs) noexcept {
   return text_style(lhs) | rhs;
 }
 
-FMT_BEGIN_DETAIL_NAMESPACE
+namespace detail {
 
 template <typename Char> struct ansi_color_escape {
   FMT_CONSTEXPR ansi_color_escape(detail::color_type text_color,
@@ -457,7 +456,7 @@ void vformat_to(buffer<Char>& buf, const text_style& ts,
   if (has_style) detail::reset_color<Char>(buf);
 }
 
-FMT_END_DETAIL_NAMESPACE
+}  // namespace detail
 
 inline void vprint(std::FILE* f, const text_style& ts, string_view fmt,
                    format_args args) {
diff --git a/include/fmt/format.h b/include/fmt/format.h
index 00a090d568d7..67d9caffde64 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -48,11 +48,6 @@
 
 #include "core.h"
 
-#ifndef FMT_BEGIN_DETAIL_NAMESPACE
-#  define FMT_BEGIN_DETAIL_NAMESPACE namespace detail {
-#  define FMT_END_DETAIL_NAMESPACE }
-#endif
-
 #if defined __cpp_inline_variables && __cpp_inline_variables >= 201606L
 #  define FMT_INLINE_VARIABLE inline
 #else
@@ -1126,7 +1121,7 @@ template <typename Locale> class format_facet : public Locale::facet {
   }
 };
 
-FMT_BEGIN_DETAIL_NAMESPACE
+namespace detail {
 
 // Returns true if value is negative, false otherwise.
 // Same as `value < 0` but doesn't produce warnings if T is an unsigned type.
@@ -3893,7 +3888,7 @@ FMT_API void format_error_code(buffer<char>& out, int error_code,
 
 FMT_API void report_error(format_func func, int error_code,
                           const char* message) noexcept;
-FMT_END_DETAIL_NAMESPACE
+}  // namespace detail
 
 FMT_API auto vsystem_error(int error_code, string_view format_str,
                            format_args args) -> std::system_error;
@@ -4264,7 +4259,7 @@ FMT_NODISCARD auto to_string(const basic_memory_buffer<Char, SIZE>& buf)
   return std::basic_string<Char>(buf.data(), size);
 }
 
-FMT_BEGIN_DETAIL_NAMESPACE
+namespace detail {
 
 template <typename Char>
 void vformat_to(buffer<Char>& buf, basic_string_view<Char> fmt,
@@ -4347,7 +4342,7 @@ extern template FMT_API auto decimal_point_impl(locale_ref) -> char;
 extern template FMT_API auto decimal_point_impl(locale_ref) -> wchar_t;
 #endif  // FMT_HEADER_ONLY
 
-FMT_END_DETAIL_NAMESPACE
+}  // namespace detail
 
 #if FMT_USE_USER_DEFINED_LITERALS
 inline namespace literals {
diff --git a/include/fmt/os.h b/include/fmt/os.h
index ec290402103b..2126424d39cb 100644
--- a/include/fmt/os.h
+++ b/include/fmt/os.h
@@ -123,10 +123,10 @@ using wcstring_view = basic_cstring_view<wchar_t>;
 #ifdef _WIN32
 FMT_API const std::error_category& system_category() noexcept;
 
-FMT_BEGIN_DETAIL_NAMESPACE
+namespace detail {
 FMT_API void format_windows_error(buffer<char>& out, int error_code,
                                   const char* message) noexcept;
-FMT_END_DETAIL_NAMESPACE
+}
 
 FMT_API std::system_error vwindows_error(int error_code, string_view format_str,
                                          format_args args);
@@ -328,7 +328,7 @@ class FMT_API file {
 // Returns the memory page size.
 long getpagesize();
 
-FMT_BEGIN_DETAIL_NAMESPACE
+namespace detail {
 
 struct buffer_size {
   buffer_size() = default;
@@ -387,7 +387,7 @@ class file_buffer final : public buffer<char> {
   }
 };
 
-FMT_END_DETAIL_NAMESPACE
+}  // namespace detail
 
 // Added {} below to work around default constructor error known to
 // occur in Xcode versions 7.2.1 and 8.2.1.
diff --git a/include/fmt/printf.h b/include/fmt/printf.h
index 5d1aeb71e14c..adef6adf837e 100644
--- a/include/fmt/printf.h
+++ b/include/fmt/printf.h
@@ -52,7 +52,7 @@ template <typename Char> class basic_printf_context {
   }
 };
 
-FMT_BEGIN_DETAIL_NAMESPACE
+namespace detail {
 
 // Checks if a value fits in int - used to avoid warnings about comparing
 // signed and unsigned integers.
@@ -553,7 +553,7 @@ void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
   }
   write(out, basic_string_view<Char>(start, to_unsigned(it - start)));
 }
-FMT_END_DETAIL_NAMESPACE
+}  // namespace detail
 
 using printf_context = basic_printf_context<char>;
 using wprintf_context = basic_printf_context<wchar_t>;