diff --git a/tests/conftest.py b/tests/conftest.py
index 7513a8ab..a4738a72 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -2,8 +2,8 @@
 
 from abc import ABC
 import asyncio
+from contextlib import contextmanager
 import multiprocessing
-import os
 import typing as _t
 from unittest.mock import patch
 
@@ -21,6 +21,16 @@
 from plugboard.utils.settings import Settings
 
 
+@contextmanager
+def override_settings(settings: Settings) -> _t.Iterator[None]:
+    """Temporarily override DI settings for a test and always reset the override."""
+    DI.settings.override_sync(settings)
+    try:
+        yield
+    finally:
+        DI.settings.reset_override_sync()
+
+
 @pytest.hookimpl(optionalhook=True)
 def pytest_asyncio_loop_factories() -> dict[str, _t.Callable[[], asyncio.AbstractEventLoop]]:
     """Configure pytest-asyncio to create event loops with uvloop."""
@@ -72,16 +82,11 @@ async def DI_teardown() -> _t.AsyncGenerator[None, None]:
 def zmq_connector_cls(zmq_pubsub_proxy: bool) -> _t.Iterator[_t.Type[ZMQConnector]]:
     """Returns the ZMQConnector class with the specified proxy setting.
 
-    Patches the env var `PLUGBOARD_FLAGS_ZMQ_PUBSUB_PROXY` to control the proxy setting.
+    Overrides settings to control the proxy setting without mutating process env.
     """
-    with patch.dict(
-        os.environ,
-        {"PLUGBOARD_FLAGS_ZMQ_PUBSUB_PROXY": str(zmq_pubsub_proxy)},
-    ):
-        testing_settings = Settings()
-        DI.settings.override_sync(testing_settings)
+    testing_settings = Settings.model_validate({"flags": {"zmq_pubsub_proxy": zmq_pubsub_proxy}})
+    with override_settings(testing_settings):
         yield ZMQConnector
-        DI.settings.reset_override_sync()
 
 
 class ComponentTestHelper(Component, ABC):
diff --git a/tests/integration/test_channel.py b/tests/integration/test_channel.py
index b4429123..c067591e 100644
--- a/tests/integration/test_channel.py
+++ b/tests/integration/test_channel.py
@@ -16,6 +16,7 @@
 from plugboard.connector.redis_channel import RedisConnector
 from plugboard.utils import DI
 from plugboard.utils.settings import Settings
+from tests.conftest import override_settings
 from tests.unit.test_channel import (  # noqa: F401
     TEST_ITEMS,
     test_channel,
@@ -28,16 +29,11 @@
 def zmq_connector_cls(zmq_pubsub_proxy: bool) -> _t.Iterator[_t.Type[ZMQConnector]]:
     """Returns the ZMQConnector class with the specified proxy setting.
 
-    Patches the env var `PLUGBOARD_FLAGS_ZMQ_PUBSUB_PROXY` to control the proxy setting.
+    Overrides settings to control the proxy setting without mutating process env.
     """
-    with patch.dict(
-        os.environ,
-        {"PLUGBOARD_FLAGS_ZMQ_PUBSUB_PROXY": str(zmq_pubsub_proxy)},
-    ):
-        testing_settings = Settings()
-        DI.settings.override_sync(testing_settings)
+    testing_settings = Settings.model_validate({"flags": {"zmq_pubsub_proxy": zmq_pubsub_proxy}})
+    with override_settings(testing_settings):
         yield ZMQConnector
-        DI.settings.reset_override_sync()
 
 
 @pytest_cases.fixture
diff --git a/tests/integration/test_connector_pubsub.py b/tests/integration/test_connector_pubsub.py
index 249165da..3ce90d58 100644
--- a/tests/integration/test_connector_pubsub.py
+++ b/tests/integration/test_connector_pubsub.py
@@ -1,8 +1,6 @@
 """Integration tests for pubsub mode connector against broker/messaging infrastructure."""
 
-import os
 import typing as _t
-from unittest.mock import patch
 
 import pytest
 import pytest_cases
@@ -13,8 +11,8 @@
     ZMQConnector,
 )
 from plugboard.connector.redis_channel import RedisConnector
-from plugboard.utils.di import DI
 from plugboard.utils.settings import Settings
+from tests.conftest import override_settings
 from tests.unit.test_connector_pubsub import (  # noqa: F401
     _HASH_SEED,
     TEST_ITEMS,
@@ -29,16 +27,11 @@
 def zmq_connector_cls(zmq_pubsub_proxy: bool) -> _t.Iterator[_t.Type[ZMQConnector]]:
     """Returns the ZMQConnector class with the specified proxy setting.
 
-    Patches the env var `PLUGBOARD_FLAGS_ZMQ_PUBSUB_PROXY` to control the proxy setting.
+    Overrides settings to control the proxy setting without mutating process env.
     """
-    with patch.dict(
-        os.environ,
-        {"PLUGBOARD_FLAGS_ZMQ_PUBSUB_PROXY": str(zmq_pubsub_proxy)},
-    ):
-        testing_settings = Settings()
-        DI.settings.override_sync(testing_settings)
+    testing_settings = Settings.model_validate({"flags": {"zmq_pubsub_proxy": zmq_pubsub_proxy}})
+    with override_settings(testing_settings):
         yield ZMQConnector
-        DI.settings.reset_override_sync()
 
 
 @pytest_cases.fixture
diff --git a/tests/unit/test_channel.py b/tests/unit/test_channel.py
index fbf6860d..abe83562 100644
--- a/tests/unit/test_channel.py
+++ b/tests/unit/test_channel.py
@@ -1,9 +1,7 @@
 """Unit tests for channels."""
 
 import asyncio
-import os
 import typing as _t
-from unittest.mock import patch
 
 import pytest
 import pytest_cases
@@ -21,6 +19,7 @@
 from plugboard.schemas import ConnectorMode, ConnectorSpec
 from plugboard.utils.di import DI
 from plugboard.utils.settings import Settings
+from tests.conftest import override_settings
 
 
 TEST_ITEMS = [
@@ -39,16 +38,11 @@
 def zmq_connector_cls(zmq_pubsub_proxy: bool) -> _t.Iterator[_t.Type[ZMQConnector]]:
     """Returns the ZMQConnector class with the specified proxy setting.
 
-    Patches the env var `PLUGBOARD_FLAGS_ZMQ_PUBSUB_PROXY` to control the proxy setting.
+    Overrides settings to control the proxy setting without mutating process env.
     """
-    with patch.dict(
-        os.environ,
-        {"PLUGBOARD_FLAGS_ZMQ_PUBSUB_PROXY": str(zmq_pubsub_proxy)},
-    ):
-        testing_settings = Settings()
-        DI.settings.override_sync(testing_settings)
+    testing_settings = Settings.model_validate({"flags": {"zmq_pubsub_proxy": zmq_pubsub_proxy}})
+    with override_settings(testing_settings):
         yield ZMQConnector
-        DI.settings.reset_override_sync()
 
 
 @pytest_cases.fixture
@@ -98,6 +92,7 @@ def connector_cls_mp(_connector_cls_mp: type[Connector]) -> type[Connector]:
 
 
 @pytest.mark.asyncio
+@pytest.mark.flaky(reruns=2)
 async def test_multiprocessing_channel(
     connector_cls_mp: type[Connector], ray_ctx: None, job_id_ctx: str
 ) -> None:
diff --git a/tests/unit/test_connector_pubsub.py b/tests/unit/test_connector_pubsub.py
index 04011bb1..17858251 100644
--- a/tests/unit/test_connector_pubsub.py
+++ b/tests/unit/test_connector_pubsub.py
@@ -3,12 +3,10 @@
 import asyncio
 from functools import lru_cache
 from itertools import cycle
-import os
 import random
 import string
 import time
 import typing as _t
-from unittest.mock import patch
 
 import pytest
 import pytest_cases
@@ -21,8 +19,8 @@
 )
 from plugboard.exceptions import ChannelClosedError
 from plugboard.schemas import ConnectorMode, ConnectorSpec
-from plugboard.utils.di import DI
 from plugboard.utils.settings import Settings
+from tests.conftest import override_settings
 
 
 @pytest_cases.fixture
@@ -30,16 +28,11 @@
 def zmq_connector_cls(zmq_pubsub_proxy: bool) -> _t.Iterator[_t.Type[ZMQConnector]]:
     """Returns the ZMQConnector class with the specified proxy setting.
 
-    Patches the env var `PLUGBOARD_FLAGS_ZMQ_PUBSUB_PROXY` to control the proxy setting.
+    Overrides settings to control the proxy setting without mutating process env.
     """
-    with patch.dict(
-        os.environ,
-        {"PLUGBOARD_FLAGS_ZMQ_PUBSUB_PROXY": str(zmq_pubsub_proxy)},
-    ):
-        testing_settings = Settings()
-        DI.settings.override_sync(testing_settings)
+    testing_settings = Settings.model_validate({"flags": {"zmq_pubsub_proxy": zmq_pubsub_proxy}})
+    with override_settings(testing_settings):
         yield ZMQConnector
-        DI.settings.reset_override_sync()
 
 
 @pytest_cases.fixture
diff --git a/tests/unit/test_state_backend.py b/tests/unit/test_state_backend.py
index 606f8b89..f581b439 100644
--- a/tests/unit/test_state_backend.py
+++ b/tests/unit/test_state_backend.py
@@ -45,6 +45,7 @@ def state_backend_cls(request: pytest.FixtureRequest) -> _t.Type[StateBackend]:
 
 
 @pytest.mark.asyncio
+@pytest.mark.flaky(reruns=2)
 @pytest.mark.parametrize(
     "job_id_fixture, metadata, exc_ctx",
     [
@@ -85,6 +86,7 @@ async def test_state_backend_init(
 
 
 @pytest.mark.asyncio
+@pytest.mark.flaky(reruns=2)
 async def test_state_backend_init_with_existing_job(
     datetime_now: str,
     state_backend_cls: _t.Type[StateBackend],