diff --git a/tests/conftest.py b/tests/conftest.py
index bc8feb7d..224f4ac5 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -1,12 +1,18 @@
 import functools
+from typing import Any, Callable, Dict
 
 import pytest
 
 from starlette.testclient import TestClient
 
+TestClientFactory = Callable[..., TestClient]
+
 
 @pytest.fixture
-def test_client_factory(anyio_backend_name, anyio_backend_options):
+def test_client_factory(
+    anyio_backend_name: str,
+    anyio_backend_options: Dict[str, Any],
+) -> TestClientFactory:
     # anyio_backend_name defined by:
     # https://anyio.readthedocs.io/en/stable/testing.html#specifying-the-backends-to-run-on
     return functools.partial(