diff --git a/tests/resources/test_resources.py b/tests/resources/test_resources.py
index ef05ae7..3a161f3 100644
--- a/tests/resources/test_resources.py
+++ b/tests/resources/test_resources.py
@@ -1,12 +1,13 @@
 # -*- coding: utf-8 -*-
 #
 # Copyright (C) 2022 CERN.
+# Copyright (C) 2024 Graz University of Technology.
 #
 # Invenio-Banners is free software; you can redistribute it and/or modify it
 # under the terms of the MIT License; see LICENSE file for more details.
 
 """Banner resource tests."""
-from datetime import date, datetime
+from datetime import date, datetime, timedelta
 
 import pytest
 from invenio_records_resources.services.errors import PermissionDeniedError
@@ -19,24 +20,26 @@
         "url_path": "/banner1",
         "category": "info",
         "active": True,
-        "start_datetime": date(2022, 7, 20),
-        "end_datetime": date(2023, 1, 29),
+        "start_datetime": date(2022, 7, 20).strftime("%Y-%m-%d %H:%M:%S"),
+        "end_datetime": (datetime.now() + timedelta(days=365)).strftime(
+            "%Y-%m-%d %H:%M:%S"
+        ),
     },
     "banner2": {
         "message": "banner2",
         "url_path": "/banner2",
         "category": "other",
         "active": False,
-        "start_datetime": date(2022, 12, 15),
-        "end_datetime": date(2023, 1, 5),
+        "start_datetime": date(2022, 12, 15).strftime("%Y-%m-%d %H:%M:%S"),
+        "end_datetime": date(2023, 1, 5).strftime("%Y-%m-%d %H:%M:%S"),
     },
     "banner3": {
         "message": "banner3",
         "url_path": "/banner3",
         "category": "warning",
         "active": True,
-        "start_datetime": date(2023, 1, 20),
-        "end_datetime": date(2023, 2, 25),
+        "start_datetime": date(2023, 1, 20).strftime("%Y-%m-%d %H:%M:%S"),
+        "end_datetime": date(2023, 2, 25).strftime("%Y-%m-%d %H:%M:%S"),
     },
 }
 
diff --git a/tests/services/test_services.py b/tests/services/test_services.py
index ceb5e25..bb6cc1b 100644
--- a/tests/services/test_services.py
+++ b/tests/services/test_services.py
@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 #
 # Copyright (C) 2022 CERN.
+# Copyright (C) 2024 Graz University of Technology.
 #
 # Invenio-Banners is free software; you can redistribute it and/or modify it
 # under the terms of the MIT License; see LICENSE file for more details.
@@ -21,7 +22,10 @@
         "message": "active",
         "url_path": "/active",
         "category": "info",
-        "end_datetime": datetime.utcnow() + timedelta(days=1),
+        "start_datetime": datetime.utcnow().strftime("%Y-%m-%d %H:%M:%S"),
+        "end_datetime": (datetime.utcnow() + timedelta(days=1)).strftime(
+            "%Y-%m-%d %H:%M:%S"
+        ),
         "active": True,
     },
     "inactive": {