diff --git a/include/fmt/os.h b/include/fmt/os.h
index b16441cb..95fafcf1 100644
--- a/include/fmt/os.h
+++ b/include/fmt/os.h
@@ -132,15 +132,8 @@ class error_code {
 
   int get() const FMT_NOEXCEPT { return value_; }
 };
-// Define FMT_USE_WINDOWS_H to 0 to disable use of windows.h.
-// All the functionality that relies on it will be disabled too.
-#ifndef _WIN32
-#  define FMT_USE_WINDOWS_H 0
-#elif !defined(FMT_USE_WINDOWS_H)
-#  define FMT_USE_WINDOWS_H 1
-#endif
 
-#if FMT_USE_WINDOWS_H
+#ifdef _WIN32
 namespace internal {
 // A converter from UTF-16 to UTF-8.
 // It is only provided for Windows since other systems support UTF-8 natively.
@@ -210,7 +203,7 @@ class windows_error : public system_error {
 // Can be used to report errors from destructors.
 FMT_API void report_windows_error(int error_code,
                                   string_view message) FMT_NOEXCEPT;
-#endif
+#endif  // _WIN32
 
 // A buffered file.
 class buffered_file {
diff --git a/src/os.cc b/src/os.cc
index acec6cfc..10a372a4 100644
--- a/src/os.cc
+++ b/src/os.cc
@@ -44,7 +44,7 @@
 #  endif  // _WIN32
 #endif    // FMT_USE_FCNTL
 
-#if FMT_USE_WINDOWS_H
+#ifdef _WIN32
 #  include <windows.h>
 #endif
 
@@ -72,7 +72,7 @@ inline std::size_t convert_rwcount(std::size_t count) { return count; }
 
 FMT_BEGIN_NAMESPACE
 
-#if FMT_USE_WINDOWS_H
+#ifdef _WIN32
 internal::utf16_to_utf8::utf16_to_utf8(wstring_view s) {
   if (int error_code = convert(s)) {
     FMT_THROW(windows_error(error_code,
@@ -145,7 +145,7 @@ void report_windows_error(int error_code,
                           fmt::string_view message) FMT_NOEXCEPT {
   report_error(internal::format_windows_error, error_code, message);
 }
-#endif  // FMT_USE_WINDOWS_H
+#endif  // _WIN32
 
 buffered_file::~buffered_file() FMT_NOEXCEPT {
   if (file_ && FMT_SYSTEM(fclose(file_)) != 0)
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 73919da0..ad391c22 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -171,18 +171,6 @@ if (FMT_PEDANTIC)
   target_compile_definitions(
     nolocale-test PRIVATE FMT_STATIC_THOUSANDS_SEPARATOR=1)
 
-  # Test that the library compiles without windows.h.
-  if (CMAKE_SYSTEM_NAME STREQUAL "Windows")
-    add_library(no-windows-h-test ../src/format.cc)
-    target_include_directories(
-      no-windows-h-test PRIVATE ${PROJECT_SOURCE_DIR}/include)
-    target_compile_definitions(no-windows-h-test PRIVATE FMT_USE_WINDOWS_H=0)
-    if (FMT_PEDANTIC)
-      target_compile_options(no-windows-h-test PRIVATE ${PEDANTIC_COMPILE_FLAGS})
-    endif ()
-    target_include_directories(no-windows-h-test SYSTEM PUBLIC gtest gmock)
-  endif ()
-
   add_test(compile-error-test ${CMAKE_CTEST_COMMAND}
     --build-and-test
     "${CMAKE_CURRENT_SOURCE_DIR}/compile-error-test"