diff --git a/swh/indexer/tests/conftest.py b/swh/indexer/tests/conftest.py
index b9211ab..bcf0af1 100644
--- a/swh/indexer/tests/conftest.py
+++ b/swh/indexer/tests/conftest.py
@@ -1,132 +1,130 @@
 # Copyright (C) 2019-2022  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 from datetime import timedelta
 from functools import partial
 import os
 from typing import List, Tuple
 from unittest.mock import patch
 
 import pytest
 from pytest_postgresql import factories
 import yaml
 
 from swh.core.db.pytest_plugin import initialize_database_for_module
 from swh.indexer.storage import IndexerStorage, get_indexer_storage
 from swh.objstorage.factory import get_objstorage
 from swh.storage import get_storage
 
 from .utils import fill_obj_storage, fill_storage
 
 TASK_NAMES: List[Tuple[str, str]] = [
     # (scheduler-task-type, task-class-test-name)
     ("index-directory-metadata", "directory_intrinsic_metadata"),
     ("index-origin-metadata", "origin_intrinsic_metadata"),
 ]
 
 
 idx_postgresql_proc = factories.postgresql_proc(
     load=[
         partial(
             initialize_database_for_module,
             modname="indexer",
             version=IndexerStorage.current_version,
         )
     ],
 )
 
 idx_storage_postgresql = factories.postgresql("idx_postgresql_proc")
 
 
 @pytest.fixture
 def indexer_scheduler(swh_scheduler):
     # Insert the expected task types within the scheduler
     for task_name, task_class_name in TASK_NAMES:
         swh_scheduler.create_task_type(
             {
                 "type": task_name,
                 "description": f"The {task_class_name} indexer testing task",
                 "backend_name": f"swh.indexer.tests.tasks.{task_class_name}",
                 "default_interval": timedelta(days=1),
                 "min_interval": timedelta(hours=6),
                 "max_interval": timedelta(days=12),
                 "num_retries": 3,
             }
         )
     return swh_scheduler
 
 
 @pytest.fixture
 def idx_storage_backend_config(idx_storage_postgresql):
     """Basic pg storage configuration with no journal collaborator for the indexer
     storage (to avoid pulling optional dependency on clients of this fixture)
 
     """
     return {
         "cls": "local",
         "db": idx_storage_postgresql.dsn,
     }
 
 
 @pytest.fixture
 def swh_indexer_config(
     swh_storage_backend_config, idx_storage_backend_config, swh_scheduler_config
 ):
     return {
         "storage": swh_storage_backend_config,
         "objstorage": {"cls": "memory"},
         "indexer_storage": idx_storage_backend_config,
         "scheduler": {"cls": "local", **swh_scheduler_config},
         "tools": {
             "name": "file",
             "version": "1:5.30-1+deb9u1",
             "configuration": {"type": "library", "debian-package": "python3-magic"},
         },
         "compute_checksums": ["blake2b512"],  # for rehash indexer
     }
 
 
 @pytest.fixture
 def idx_storage(swh_indexer_config):
     """An instance of in-memory indexer storage that gets injected into all
     indexers classes.
 
     """
     idx_storage_config = swh_indexer_config["indexer_storage"]
     return get_indexer_storage(**idx_storage_config)
 
 
 @pytest.fixture
 def storage(swh_indexer_config):
     """An instance of in-memory storage that gets injected into all indexers
     classes.
 
     """
     storage = get_storage(**swh_indexer_config["storage"])
     fill_storage(storage)
     return storage
 
 
 @pytest.fixture
 def obj_storage(swh_indexer_config):
     """An instance of in-memory objstorage that gets injected into all indexers
     classes.
 
     """
     objstorage = get_objstorage(**swh_indexer_config["objstorage"])
     fill_obj_storage(objstorage)
-    with patch.dict(
-        "swh.objstorage.factory._STORAGE_CLASSES", {"memory": lambda: objstorage}
-    ):
+    with patch("swh.indexer.indexer.get_objstorage", return_value=objstorage):
         yield objstorage
 
 
 @pytest.fixture
 def swh_config(swh_indexer_config, monkeypatch, tmp_path):
     conffile = os.path.join(str(tmp_path), "indexer.yml")
     with open(conffile, "w") as f:
         f.write(yaml.dump(swh_indexer_config))
     monkeypatch.setenv("SWH_CONFIG_FILENAME", conffile)
     return conffile