diff --git a/src/os.cc b/src/os.cc
index 7873fe6f0cc6b..5344144caf85f 100644
--- a/src/os.cc
+++ b/src/os.cc
@@ -213,22 +213,25 @@ int buffered_file::descriptor() const {
 }
 
 #if FMT_USE_FCNTL
-file::file(cstring_view path, int oflag) {
 #  ifdef _WIN32
-  using mode_t = int;
+using mode_t = int;
 #  endif
-  constexpr mode_t mode =
-      S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
+constexpr mode_t default_open_mode =
+    S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
+
+file::file(cstring_view path, int oflag) {
 #  if defined(_WIN32) && !defined(__MINGW32__)
   fd_ = -1;
   auto converted = detail::utf8_to_utf16(string_view(path.c_str()));
-  FMT_POSIX_CALL(wsopen_s(&fd_, converted.c_str(), oflag, _SH_DENYNO, mode));
+  auto err =
+      _wsopen_s(&fd_, converted.c_str(), oflag, _SH_DENYNO, default_open_mode);
 #  else
   FMT_RETRY(fd_, FMT_POSIX_CALL(open(path.c_str(), oflag, mode)));
+  auto err = errno;
 #  endif
   if (fd_ == -1)
     FMT_THROW(
-        system_error(errno, FMT_STRING("cannot open file {}"), path.c_str()));
+        system_error(err, FMT_STRING("cannot open file {}"), path.c_str()));
 }
 
 file::~file() noexcept {
@@ -357,12 +360,10 @@ buffered_file file::fdopen(const char* mode) {
 #  if defined(_WIN32) && !defined(__MINGW32__)
 file file::open_windows_file(wcstring_view path, int oflag) {
   int fd_ = -1;
-  using mode_t = int;
-  constexpr mode_t mode =
-      S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
-  FMT_POSIX_CALL(wsopen_s(&fd_, path.c_str(), oflag, _SH_DENYNO, mode));
+  auto res =
+      _wsopen_s(&fd_, path.c_str(), oflag, _SH_DENYNO, default_open_mode);
   if (fd_ == -1)
-    FMT_THROW(system_error(errno, FMT_STRING("cannot open file {}"),
+    FMT_THROW(system_error(res, FMT_STRING("cannot open file {}"),
                            detail::utf16_to_utf8(path.c_str()).c_str()));
   return file(fd_);
 }
diff --git a/test/posix-mock-test.cc b/test/posix-mock-test.cc
index 5fd5251fddcfe..32078bf8a5966 100644
--- a/test/posix-mock-test.cc
+++ b/test/posix-mock-test.cc
@@ -72,17 +72,6 @@ int test::open(const char* path, int oflag, int mode) {
   EMULATE_EINTR(open, -1);
   return ::open(path, oflag, mode);
 }
-#else
-errno_t test::sopen_s(int* pfh, const char* filename, int oflag, int shflag,
-                      int pmode) {
-  EMULATE_EINTR(open, EINTR);
-  return _sopen_s(pfh, filename, oflag, shflag, pmode);
-}
-errno_t test::wsopen_s(int* pfh, const wchar_t* filename, int oflag, int shflag,
-                       int pmode) {
-  EMULATE_EINTR(open, EINTR);
-  return _wsopen_s(pfh, filename, oflag, shflag, pmode);
-}
 #endif
 
 #ifndef _WIN32
@@ -225,11 +214,11 @@ TEST(os_test, getpagesize) {
 }
 
 TEST(file_test, open_retry) {
+#  ifndef _WIN32
   write_file("temp", "there must be something here");
   std::unique_ptr<file> f{nullptr};
   EXPECT_RETRY(f.reset(new file("temp", file::RDONLY)), open,
                "cannot open file temp");
-#  ifndef _WIN32
   char c = 0;
   f->read(&c, 1);
 #  endif
diff --git a/test/posix-mock.h b/test/posix-mock.h
index bbb9ab7792a62..4f2a42c1b5107 100644
--- a/test/posix-mock.h
+++ b/test/posix-mock.h
@@ -37,10 +37,6 @@ int fstat(int fd, struct stat* buf);
 #else
 typedef unsigned size_t;
 typedef int ssize_t;
-errno_t sopen_s(int* pfh, const char* filename, int oflag, int shflag,
-                int pmode);
-errno_t wsopen_s(int* pfh, const wchar_t* filename, int oflag, int shflag,
-                int pmode);
 #endif
 
 #ifndef _WIN32