diff --git a/src/scitacean/client.py b/src/scitacean/client.py
index 4519e074..01484ea0 100644
--- a/src/scitacean/client.py
+++ b/src/scitacean/client.py
@@ -711,8 +711,8 @@ def query_datasets(
         self,
         fields: dict[str, Any],
         *,
-        limit: Optional[int] = None,
-        order: Optional[str] = None,
+        limit: int | None = None,
+        order: str | None = None,
         strict_validation: bool = False,
     ) -> list[model.DownloadDataset]:
         """Query for datasets in SciCat.
@@ -783,7 +783,7 @@ def query_datasets(
         )
         params = {"fields": params_model(**fields).model_dump_json()}
 
-        limits: dict[str, Union[str, int]] = {}
+        limits: dict[str, str | int] = {}
         if order is not None:
             limits["order"] = order
         if limit is not None:
@@ -1154,7 +1154,7 @@ def _call_endpoint(
         url: str,
         operation: str,
         data: model.BaseModel | None = None,
-        params: Optional[dict[str, str]] = None,
+        params: dict[str, str] | None = None,
     ) -> Any:
         full_url = _url_concat(self._base_url, url)
         logger = get_logger()
diff --git a/tests/client/query_client_test.py b/tests/client/query_client_test.py
index 49a97950..81d8a7ba 100644
--- a/tests/client/query_client_test.py
+++ b/tests/client/query_client_test.py
@@ -1,7 +1,6 @@
 # SPDX-License-Identifier: BSD-3-Clause
 # Copyright (c) 2024 SciCat Project (https://github.com/SciCatProject/scitacean)
 
-from typing import Union
 
 import pytest
 from dateutil.parser import parse as parse_datetime
@@ -10,9 +9,7 @@
 from scitacean.testing.backend import skip_if_not_backend
 from scitacean.testing.backend.config import SciCatAccess
 
-UPLOAD_DATASETS: dict[
-    str, Union[model.UploadDerivedDataset, model.UploadRawDataset]
-] = {
+UPLOAD_DATASETS: dict[str, model.UploadDerivedDataset | model.UploadRawDataset] = {
     "raw1": model.UploadRawDataset(
         ownerGroup="PLACEHOLDER",
         accessGroups=["uu", "faculty"],