diff --git a/python_tests/test_api.py b/python_tests/test_api.py
index 0811c229..e50f2501 100644
--- a/python_tests/test_api.py
+++ b/python_tests/test_api.py
@@ -159,7 +159,7 @@ class APITestCase(TestCase):
 
     def test_report_preference_when_typo_mode(self) -> None:
         storage = optuna.storages.InMemoryStorage()
-        study = create_study(storage=storage)
+        study = create_study(storage=storage, n_generate=3)
         for _ in range(3):
             trial = study.ask()
             study.mark_comparison_ready(trial)
diff --git a/python_tests/test_preferential_history.py b/python_tests/test_preferential_history.py
index 7f184e51..ab524b90 100644
--- a/python_tests/test_preferential_history.py
+++ b/python_tests/test_preferential_history.py
@@ -15,7 +15,7 @@ from .storage_supplier import StorageSupplier
 @parametrize_storages
 def test_report_and_get_choices(storage_supplier: Callable[[], StorageSupplier]) -> None:
     with storage_supplier() as storage:
-        study = create_study(storage=storage)
+        study = create_study(storage=storage, n_generate=5)
         for _ in range(5):
             trial = study.ask()
             trial.suggest_float("x", 0, 1)