diff --git a/tests/integration/study_data_blueprint/test_st_storage.py b/tests/integration/study_data_blueprint/test_st_storage.py
index cdd0b464c7..8f57b1297e 100644
--- a/tests/integration/study_data_blueprint/test_st_storage.py
+++ b/tests/integration/study_data_blueprint/test_st_storage.py
@@ -240,7 +240,7 @@ def test_lifecycle__nominal(
             json=[siemens_battery_id],
         )
         assert res.status_code == 204, res.json()
-        assert res.text in {"", "null"}  # Old FastAPI versions return 'null'.
+        assert not res.text
 
         # deletion of short-term storages with empty list
         res = client.request(
@@ -250,7 +250,7 @@ def test_lifecycle__nominal(
             json=[],
         )
         assert res.status_code == 204, res.json()
-        assert res.text in {"", "null"}  # Old FastAPI versions return 'null'.
+        assert not res.text
 
         # deletion of short-term storages with multiple IDs
         res = client.post(
@@ -278,7 +278,7 @@ def test_lifecycle__nominal(
             json=[siemens_battery_id1, siemens_battery_id2],
         )
         assert res.status_code == 204, res.json()
-        assert res.text in {"", "null"}  # Old FastAPI versions return 'null'.
+        assert not res.text
 
         # Check the removal
         res = client.get(