diff --git a/include/fmt/args.h b/include/fmt/args.h
index 10c1eb8f44c1..d45b965bc51a 100644
--- a/include/fmt/args.h
+++ b/include/fmt/args.h
@@ -8,7 +8,7 @@
 #ifndef FMT_ARGS_H_
 #define FMT_ARGS_H_
 
-#ifndef FMT_IMPORT_STD
+#if !defined(FMT_IMPORT_STD) && !defined(FMT_MODULE)
 #  include <functional>  // std::reference_wrapper
 #  include <memory>      // std::unique_ptr
 #  include <vector>
diff --git a/include/fmt/base.h b/include/fmt/base.h
index a1af876f06b7..396d268faaab 100644
--- a/include/fmt/base.h
+++ b/include/fmt/base.h
@@ -15,11 +15,11 @@
 #  include <string.h>  // strlen
 #endif
 
-#ifndef FMT_IMPORT_STD
+#if !defined(FMT_IMPORT_STD) && !defined(FMT_MODULE)
 // <cstddef> is also included transitively from <type_traits>.
 #  include <cstddef>      // std::byte
 #  include <type_traits>  // std::enable_if
-#else
+#elif !defined(FMT_MODULE)
 import std;
 #endif
 
diff --git a/include/fmt/chrono.h b/include/fmt/chrono.h
index 77d0403246ac..3406a4a673f2 100644
--- a/include/fmt/chrono.h
+++ b/include/fmt/chrono.h
@@ -8,7 +8,7 @@
 #ifndef FMT_CHRONO_H_
 #define FMT_CHRONO_H_
 
-#ifndef FMT_IMPORT_STD
+#if !defined(FMT_IMPORT_STD) && !defined(FMT_MODULE)
 #  include <algorithm>
 #  include <chrono>
 #  include <cmath>    // std::isfinite
diff --git a/include/fmt/compile.h b/include/fmt/compile.h
index d77de3581839..a98e1bc0531b 100644
--- a/include/fmt/compile.h
+++ b/include/fmt/compile.h
@@ -8,7 +8,7 @@
 #ifndef FMT_COMPILE_H_
 #define FMT_COMPILE_H_
 
-#ifndef FMT_IMPORT_STD
+#if !defined(FMT_IMPORT_STD) && !defined(FMT_MODULE)
 #  include <iterator>  // std::back_inserter
 #endif
 
diff --git a/include/fmt/format-inl.h b/include/fmt/format-inl.h
index 73f40f3d6bfe..db6d74d4c95f 100644
--- a/include/fmt/format-inl.h
+++ b/include/fmt/format-inl.h
@@ -8,16 +8,19 @@
 #ifndef FMT_FORMAT_INL_H_
 #define FMT_FORMAT_INL_H_
 
-#ifndef FMT_IMPORT_STD
+#if !defined(FMT_IMPORT_STD) && !defined(FMT_MODULE)
 #  include <algorithm>
 #  include <cmath>
 #  include <exception>
 #endif
-#include <cerrno>  // errno
-#include <climits>
 
-#if !defined(FMT_STATIC_THOUSANDS_SEPARATOR) && !defined(FMT_IMPORT_STD)
-#  include <locale>
+#ifndef FMT_MODULE
+#  include <cerrno>  // errno
+#  include <climits>
+
+#  if !defined(FMT_STATIC_THOUSANDS_SEPARATOR) && !defined(FMT_IMPORT_STD)
+#    include <locale>
+#  endif
 #endif
 
 #if defined(_WIN32) && !defined(FMT_USE_WRITE_CONSOLE)
diff --git a/include/fmt/format.h b/include/fmt/format.h
index fa8debc13b71..bfdb2e0e3fe8 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -38,7 +38,7 @@
 #  define FMT_REMOVE_TRANSITIVE_INCLUDES
 #endif
 
-#ifndef FMT_IMPORT_STD
+#if !defined(FMT_IMPORT_STD) && !defined(FMT_MODULE)
 #  include <cmath>             // std::signbit
 #  include <cstdint>           // uint32_t
 #  include <cstring>           // std::memcpy
@@ -57,14 +57,14 @@
 
 // Checking FMT_CPLUSPLUS for warning suppression in MSVC.
 #if FMT_HAS_INCLUDE(<bit>) && FMT_CPLUSPLUS > 201703L && \
-    !defined(FMT_IMPORT_STD)
+    !defined(FMT_IMPORT_STD) && !defined(FMT_MODULE)
 #  include <bit>  // std::bit_cast
 #endif
 
 // libc++ supports string_view in pre-c++17.
 #if FMT_HAS_INCLUDE(<string_view>) && \
     (FMT_CPLUSPLUS >= 201703L || defined(_LIBCPP_VERSION))
-#  ifndef FMT_IMPORT_STD
+#  if !defined(FMT_IMPORT_STD) && !defined(FMT_MODULE)
 #    include <string_view>
 #  endif
 #  define FMT_USE_STRING_VIEW
diff --git a/include/fmt/os.h b/include/fmt/os.h
index fae18f166fb9..5462661a026a 100644
--- a/include/fmt/os.h
+++ b/include/fmt/os.h
@@ -8,17 +8,19 @@
 #ifndef FMT_OS_H_
 #define FMT_OS_H_
 
-#include <cerrno>
-#ifndef FMT_IMPORT_STD
-#  include <cstddef>
-#  include <cstdio>
-#  include <system_error>  // std::system_error
+#ifndef FMT_MODULE
+#  include <cerrno>
+#  ifndef FMT_IMPORT_STD
+#    include <cstddef>
+#    include <cstdio>
+#    include <system_error>  // std::system_error
+#  endif
 #endif
 
 #include "format.h"
 
 #if defined __APPLE__ || defined(__FreeBSD__)
-#  if FMT_HAS_INCLUDE(<xlocale.h>)
+#  if FMT_HAS_INCLUDE(<xlocale.h>) && !defined(FMT_MODULE)
 #    include <xlocale.h>  // for LC_NUMERIC_MASK on OS X
 #  endif
 #endif
diff --git a/include/fmt/ostream.h b/include/fmt/ostream.h
index f05e0dcde035..0be26709dcd0 100644
--- a/include/fmt/ostream.h
+++ b/include/fmt/ostream.h
@@ -8,7 +8,7 @@
 #ifndef FMT_OSTREAM_H_
 #define FMT_OSTREAM_H_
 
-#ifndef FMT_IMPORT_STD
+#if !defined(FMT_IMPORT_STD) && !defined(FMT_MODULE)
 #  include <fstream>  // std::filebuf
 #endif
 
diff --git a/include/fmt/printf.h b/include/fmt/printf.h
index e6cd5c3d5d22..3b2b9b4be8b3 100644
--- a/include/fmt/printf.h
+++ b/include/fmt/printf.h
@@ -8,7 +8,7 @@
 #ifndef FMT_PRINTF_H_
 #define FMT_PRINTF_H_
 
-#ifndef FMT_IMPORT_STD
+#if !defined(FMT_IMPORT_STD) && !defined(FMT_MODULE)
 #  include <algorithm>  // std::max
 #  include <limits>     // std::numeric_limits
 #endif
diff --git a/include/fmt/ranges.h b/include/fmt/ranges.h
index 2cd5d37faf52..f3377ab5c312 100644
--- a/include/fmt/ranges.h
+++ b/include/fmt/ranges.h
@@ -8,7 +8,7 @@
 #ifndef FMT_RANGES_H_
 #define FMT_RANGES_H_
 
-#ifndef FMT_IMPORT_STD
+#if !defined(FMT_IMPORT_STD) && !defined(FMT_MODULE)
 #  include <initializer_list>
 #  include <iterator>
 #  include <string>
diff --git a/include/fmt/std.h b/include/fmt/std.h
index 99528514ebd1..5f1f403c41ee 100644
--- a/include/fmt/std.h
+++ b/include/fmt/std.h
@@ -8,7 +8,7 @@
 #ifndef FMT_STD_H_
 #define FMT_STD_H_
 
-#ifndef FMT_IMPORT_STD
+#if !defined(FMT_IMPORT_STD) && !defined(FMT_MODULE)
 #  include <atomic>
 #  include <bitset>
 #  include <complex>
@@ -29,7 +29,7 @@
 #  include <version>
 #endif
 
-#ifndef FMT_IMPORT_STD
+#if !defined(FMT_IMPORT_STD) && !defined(FMT_MODULE)
 // Checking FMT_CPLUSPLUS for warning suppression in MSVC.
 #  if FMT_CPLUSPLUS >= 201703L
 #    if FMT_HAS_INCLUDE(<filesystem>)
diff --git a/include/fmt/xchar.h b/include/fmt/xchar.h
index b8bb1359c0e3..31bdccdb97ee 100644
--- a/include/fmt/xchar.h
+++ b/include/fmt/xchar.h
@@ -8,7 +8,7 @@
 #ifndef FMT_XCHAR_H_
 #define FMT_XCHAR_H_
 
-#ifndef FMT_IMPORT_STD
+#if !defined(FMT_IMPORT_STD) && !defined(FMT_MODULE)
 #  include <cwchar>
 #endif
 
@@ -16,7 +16,8 @@
 #include "format.h"
 #include "ranges.h"
 
-#if !defined(FMT_STATIC_THOUSANDS_SEPARATOR) && !defined(FMT_IMPORT_STD)
+#if !defined(FMT_STATIC_THOUSANDS_SEPARATOR) && !defined(FMT_IMPORT_STD) && \
+    !defined(FMT_MODULE)
 #  include <locale>
 #endif
 
diff --git a/src/fmt.cc b/src/fmt.cc
index 364f4fa1290b..108f15312b3b 100644
--- a/src/fmt.cc
+++ b/src/fmt.cc
@@ -4,6 +4,7 @@ module;
 // to prevent attachment to this module.
 #ifndef FMT_IMPORT_STD
 #  include <algorithm>
+#  include <bitset>
 #  include <chrono>
 #  include <cmath>
 #  include <complex>