diff --git a/tests/handlers/test_oidc.py b/tests/handlers/test_oidc.py
index d485af52fd..23ea1e3543 100644
--- a/tests/handlers/test_oidc.py
+++ b/tests/handlers/test_oidc.py
@@ -17,30 +17,15 @@ from urllib.parse import parse_qs, urlparse
 
 from mock import Mock, patch
 
-import attr
 import pymacaroons
 
-from twisted.python.failure import Failure
-from twisted.web._newclient import ResponseDone
-
 from synapse.handlers.oidc_handler import OidcError, OidcMappingProvider
 from synapse.handlers.sso import MappingException
 from synapse.types import UserID
 
+from tests.test_utils import FakeResponse
 from tests.unittest import HomeserverTestCase, override_config
 
-
-@attr.s
-class FakeResponse:
-    code = attr.ib()
-    body = attr.ib()
-    phrase = attr.ib()
-
-    def deliverBody(self, protocol):
-        protocol.dataReceived(self.body)
-        protocol.connectionLost(Failure(ResponseDone()))
-
-
 # These are a few constants that are used as config parameters in the tests.
 ISSUER = "https://issuer/"
 CLIENT_ID = "test-client-id"
diff --git a/tests/test_utils/__init__.py b/tests/test_utils/__init__.py
index d232b72264..6873d45eb6 100644
--- a/tests/test_utils/__init__.py
+++ b/tests/test_utils/__init__.py
@@ -22,6 +22,11 @@ import warnings
 from asyncio import Future
 from typing import Any, Awaitable, Callable, TypeVar
 
+import attr
+
+from twisted.python.failure import Failure
+from twisted.web.client import ResponseDone
+
 TV = TypeVar("TV")
 
 
@@ -80,3 +85,25 @@ def setup_awaitable_errors() -> Callable[[], None]:
     sys.unraisablehook = unraisablehook  # type: ignore
 
     return cleanup
+
+
+@attr.s
+class FakeResponse:
+    """A fake twisted.web.IResponse object
+
+    there is a similar class at treq.test.test_response, but it lacks a `phrase`
+    attribute, and didn't support deliverBody until recently.
+    """
+
+    # HTTP response code
+    code = attr.ib(type=int)
+
+    # HTTP response phrase (eg b'OK' for a 200)
+    phrase = attr.ib(type=bytes)
+
+    # body of the response
+    body = attr.ib(type=bytes)
+
+    def deliverBody(self, protocol):
+        protocol.dataReceived(self.body)
+        protocol.connectionLost(Failure(ResponseDone()))