diff --git a/include/fmt/core.h b/include/fmt/core.h
index bf95038d61d35..67fca8b61ab6a 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -238,6 +238,7 @@
 
 #ifndef FMT_MODULE_EXPORT
 #  define FMT_MODULE_EXPORT
+#  define FMT_MODULE_EXPORT_CONSTANT static
 #  define FMT_MODULE_EXPORT_BEGIN
 #  define FMT_MODULE_EXPORT_END
 #  define FMT_BEGIN_DETAIL_NAMESPACE namespace detail {
diff --git a/include/fmt/os.h b/include/fmt/os.h
index c447831e5562d..2d14953a8beee 100644
--- a/include/fmt/os.h
+++ b/include/fmt/os.h
@@ -394,7 +394,7 @@ struct ostream_params {
 
 FMT_END_DETAIL_NAMESPACE
 
-static constexpr detail::buffer_size buffer_size;
+FMT_MODULE_EXPORT_CONSTANT constexpr detail::buffer_size buffer_size;
 
 /** A fast output stream which is not thread-safe. */
 class FMT_API ostream final : private detail::buffer<char> {
diff --git a/src/fmt.cc b/src/fmt.cc
index d0d6e7fb348d4..23234e7a597f3 100644
--- a/src/fmt.cc
+++ b/src/fmt.cc
@@ -2,6 +2,9 @@ module;
 #ifndef __cpp_modules
 #  error Module not supported.
 #endif
+#ifdef _MSC_VER
+#  pragma warning(disable : 4702)
+#endif
 
 // put all implementation-provided headers into the global module fragment
 // to prevent attachment to this module
@@ -71,6 +74,7 @@ module;
 export module fmt;
 
 #define FMT_MODULE_EXPORT export
+#define FMT_MODULE_EXPORT_CONSTANT
 #define FMT_MODULE_EXPORT_BEGIN export {
 #define FMT_MODULE_EXPORT_END }
 #define FMT_BEGIN_DETAIL_NAMESPACE \
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index dcf3f4ac258e4..720bea19e7335 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -99,8 +99,10 @@ if (FMT_CAN_MODULE)
 
   add_fmt_test(module-test MODULE)
   if (MSVC)
-    target_compile_options(test-module PRIVATE /utf-8)
-    target_compile_options(module-test PRIVATE /utf-8)
+    target_compile_options(test-module PRIVATE /utf-8 /Zc:__cplusplus
+                           /Zc:externConstexpr /Zc:inline)
+    target_compile_options(module-test PRIVATE /utf-8 /Zc:__cplusplus
+                           /Zc:externConstexpr /Zc:inline)
   endif ()
 endif ()