diff --git a/quetz/database.py b/quetz/database.py
index 0ba97cf8..b4809cb7 100644
--- a/quetz/database.py
+++ b/quetz/database.py
@@ -65,9 +65,7 @@ def on_close(dbapi_conn, conn_record):
 def get_session_maker(
     bind: sqlalchemy.engine.Engine | sqlalchemy.engine.Connection,
 ) -> Callable[[], sessionmaker]:
-    return sessionmaker(
-        autocommit=False, autoflush=True, bind=bind, expire_on_commit=True
-    )
+    return sessionmaker(autocommit=False, bind=bind)
 
 
 def get_session(config: Config | None) -> Session:
diff --git a/quetz/testing/fixtures.py b/quetz/testing/fixtures.py
index d7d27a19..0e0a4a78 100644
--- a/quetz/testing/fixtures.py
+++ b/quetz/testing/fixtures.py
@@ -19,7 +19,9 @@
 
 def pytest_configure(config):
     pytest.quetz_variables = {
-        var: value for var, value in os.environ.items() if var.startswith("QUETZ_")
+        var: value
+        for var, value in os.environ.items()
+        if var.startswith("QUETZ_") and not var.startswith("QUETZ_TEST")
     }
     for var in pytest.quetz_variables:
         del os.environ[var]
@@ -158,10 +160,10 @@ def wrapper(*args, **kwargs):
 @pytest.fixture
 def db(
     session_maker: sqlalchemy.orm.sessionmaker,
-) -> Iterator[sqlalchemy.orm.Session]:
+) -> sqlalchemy.orm.Session:
     with mock.patch("quetz.database.get_session", session_maker):
         with session_maker() as db:
-            yield db
+            return db
 
 
 @pytest.fixture
diff --git a/quetz/tests/api/test_users.py b/quetz/tests/api/test_users.py
index 4f3473bd..9a643039 100644
--- a/quetz/tests/api/test_users.py
+++ b/quetz/tests/api/test_users.py
@@ -176,7 +176,6 @@ def test_delete_user_permission(
     other_user, auth_client, db, user_role, target_user, expected_status, user, api_keys
 ):
     response = auth_client.delete(f"/api/users/{target_user}")
-
     deleted_user = db.query(User).filter(User.username == target_user).one_or_none()
 
     if expected_status == 200:
@@ -196,11 +195,12 @@ def test_delete_user_permission(
         assert deleted_user.api_keys_user
 
     # check if other users were not accidently removed
-    existing_user = db.query(User).filter(User.username != target_user).one_or_none()
-    assert existing_user
-    assert existing_user.profile
-    assert existing_user.api_keys_owner
-    assert existing_user.api_keys_user
+    existing_users = db.query(User).filter(User.username != target_user).all()
+    assert existing_users
+    for existing_user in existing_users:
+        assert existing_user.profile
+        assert existing_user.api_keys_owner
+        assert existing_user.api_keys_user
 
 
 @pytest.mark.parametrize("user_role", ["owner"])
diff --git a/quetz/tests/test_workers.py b/quetz/tests/test_workers.py
index b8a1353f..c5436eea 100644
--- a/quetz/tests/test_workers.py
+++ b/quetz/tests/test_workers.py
@@ -8,6 +8,7 @@
 
 from quetz.authorization import Rules
 from quetz.dao import Dao
+from quetz.database import get_session_maker
 from quetz.db_models import User
 from quetz.tasks.workers import RQManager, SubprocessWorker, ThreadingWorker
 
@@ -124,19 +125,23 @@ def function_with_dao(dao: Dao):
 
 
 @pytest.fixture
-def db_cleanup(config):
+def db_cleanup(engine):
     # we can't use the db fixture for cleaning up because
     # it automatically rollsback all operations
 
     yield
 
-    from quetz.database import get_session
-
-    with get_session(config) as db:
-        user = db.query(User).one_or_none()
-        if user:
-            db.delete(user)
-            db.commit()
+    with engine.connect() as con:
+        session_maker = get_session_maker(con)
+        with session_maker() as db:
+            user = db.query(User).one_or_none()
+            if user:
+                db.delete(user)
+                db.commit()
+
+        with session_maker() as db:
+            user = db.query(User).one_or_none()
+            assert user is None
 
 
 @pytest.mark.asyncio