diff --git a/port/win/env_win.cc b/port/win/env_win.cc
index 87b4eb159..5073944f5 100644
--- a/port/win/env_win.cc
+++ b/port/win/env_win.cc
@@ -253,7 +253,7 @@ Status WinEnvIO::OpenWritableFile(const std::string& fname,
   DWORD fileFlags = FILE_ATTRIBUTE_NORMAL;
 
   if (local_options.use_direct_writes && !local_options.use_mmap_writes) {
-    fileFlags = FILE_FLAG_NO_BUFFERING;
+    fileFlags = FILE_FLAG_NO_BUFFERING | FILE_FLAG_WRITE_THROUGH;
   }
 
   // Desired access. We are want to write only here but if we want to memory
diff --git a/port/win/io_win.cc b/port/win/io_win.cc
index 9403c829d..8cdd456d6 100644
--- a/port/win/io_win.cc
+++ b/port/win/io_win.cc
@@ -880,7 +880,7 @@ inline
 Status WinWritableImpl::SyncImpl() {
   Status s;
   // Calls flush buffers
-  if (fsync(file_data_->GetFileHandle()) < 0) {
+  if (!file_data_->use_direct_io() && fsync(file_data_->GetFileHandle()) < 0) {
     auto lastError = GetLastError();
     s = IOErrorFromWindowsError(
         "fsync failed at Sync() for: " + file_data_->GetName(), lastError);
@@ -961,7 +961,11 @@ Status WinWritableFile::Sync() {
   return SyncImpl();
 }
 
-Status WinWritableFile::Fsync() { return SyncImpl(); }
+Status WinWritableFile::Fsync() {
+  return SyncImpl();
+}
+
+bool WinWritableFile::IsSyncThreadSafe() const { return true; }
 
 uint64_t WinWritableFile::GetFileSize() {
   return GetFileNextWriteOffset();
diff --git a/port/win/io_win.h b/port/win/io_win.h
index 2c1d5a1ea..74a99ec93 100644
--- a/port/win/io_win.h
+++ b/port/win/io_win.h
@@ -368,6 +368,8 @@ class WinWritableFile : private WinFileData,
 
   virtual Status Fsync() override;
 
+  virtual bool IsSyncThreadSafe() const override;
+
   // Indicates if the class makes use of direct I/O
   // Use PositionedAppend
   virtual bool use_direct_io() const override;