diff --git a/ptvp35/__init__.py b/ptvp35/__init__.py
index d736f73..a9a8907 100644
--- a/ptvp35/__init__.py
+++ b/ptvp35/__init__.py
@@ -3,7 +3,6 @@ import concurrent.futures
 import json
 import pathlib
 import pickle
-import shutil
 import traceback
 from io import StringIO
 from typing import Any, Optional, IO, Type, Hashable
@@ -226,7 +225,11 @@ class DbConnection:
             await self._background_cycle()
 
     def _copy_sync(self):
-        shutil.copyfile(self.__path_backup, self.__path)
+        db = {}
+        with open(self.__path_backup) as file:
+            self.io2db(file, db)
+        with open(self.__path, 'w') as file:
+            self.db2io(db, file)
 
     async def _copy(self):
         with concurrent.futures.ThreadPoolExecutor() as pool: