diff --git a/ptvp35/__init__.py b/ptvp35/__init__.py
index eb7617a..f94666f 100644
--- a/ptvp35/__init__.py
+++ b/ptvp35/__init__.py
@@ -1,5 +1,6 @@
 import asyncio
 import json
+import os
 import pathlib
 import pickle
 import threading
@@ -177,9 +178,14 @@ class DbConnection:
         self.db2io(bufferdb, buffer)
         return buffer
 
+    def _file_write(self, line: str):
+        self.__file.write(line)
+        self.__file.flush()
+        os.fsync(self.__file.fileno())
+
     async def _dump_compressed_buffer(self):
         buffer = self._compress_buffer()
-        await self.__loop.run_in_executor(None, self.__file.write, buffer.getvalue())
+        await self.__loop.run_in_executor(None, self._file_write, buffer.getvalue())
 
     async def _do_dump_buffer(self):
         await self._dump_compressed_buffer()