diff --git a/tests/server.py b/tests/server.py
index d2eeee4d9f..1e6b160409 100644
--- a/tests/server.py
+++ b/tests/server.py
@@ -35,6 +35,7 @@ from typing import (
 from unittest.mock import Mock
 
 import attr
+from twisted.web.iweb import IRequest
 from typing_extensions import Deque
 from zope.interface import implementer
 
@@ -277,7 +278,7 @@ class FakeSite:
         self._resource = resource
         self.reactor = reactor
 
-    def getResourceFor(self, request):
+    def getResourceFor(self, request: IRequest) -> IResource:
         return self._resource