diff --git a/archive/v1/src/tasks/backup.py b/archive/v1/src/tasks/backup.py
index ff48d0e896..45b0266339 100644
--- a/archive/v1/src/tasks/backup.py
+++ b/archive/v1/src/tasks/backup.py
@@ -320,8 +320,11 @@ async def execute_backup(self, session: AsyncSession) -> Dict[str, Any]:
         export_data["tables"]["pose_detections_recent"] = pose_data
         
         # Write compressed JSON
-        with gzip.open(backup_path, 'wt', encoding='utf-8') as f:
-            json.dump(export_data, f, indent=2, default=str)
+        def _write_json_sync():
+            with gzip.open(backup_path, 'wt', encoding='utf-8') as f:
+                json.dump(export_data, f, indent=2, default=str)
+
+        await asyncio.to_thread(_write_json_sync)
         
         backup_size_mb = self._get_file_size_mb(backup_path)