diff --git a/backend/services/backups.py b/backend/services/backups.py
index 0716262..e1e8283 100644
--- a/backend/services/backups.py
+++ b/backend/services/backups.py
@@ -14,7 +14,7 @@ import logging
 import os
 import shutil
 import time
-from datetime import datetime, timezone
+from datetime import UTC, datetime
 from pathlib import Path
 from typing import Any
 
@@ -145,7 +145,7 @@ def list_backup_files(vault_name: str, relative_path: str) -> list[dict[str, Any
             except (ValueError, TypeError):
                 continue
             try:
-                dt = datetime.fromtimestamp(ts, tz=timezone.utc).isoformat()
+                dt = datetime.fromtimestamp(ts, tz=UTC).isoformat()
             except (OSError, OverflowError, ValueError) as ts_err:
                 logger.warning(f"Skipping backup with invalid timestamp {ts}: {ts_err}")
                 continue
@@ -219,7 +219,7 @@ def diff_backup(
                 status=500,
                 details={"vault": vault_name, "path": path, "version": ts},
             ) from e
-        dt = datetime.fromtimestamp(ts, tz=timezone.utc).strftime("%Y-%m-%d %H:%M:%S UTC")
+        dt = datetime.fromtimestamp(ts, tz=UTC).strftime("%Y-%m-%d %H:%M:%S UTC")
         return content, f"{path}@{dt}"
 
     try: