diff --git a/4887.bugfix b/4887.bugfix
new file mode 100644
index 0000000000..f7c953aef4
--- /dev/null
+++ b/4887.bugfix
@@ -0,0 +1 @@
+fix test_auto_create_auto_join_where_no_consent
diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
index eb81556080..68f73d3793 100644
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -29,7 +29,6 @@ from synapse.api.errors import (
     RegistrationError,
     SynapseError,
 )
-
 from synapse.config.server import is_threepid_reserved
 from synapse.http.client import CaptchaServerHttpClient
 from synapse.http.servlet import assert_params_in_dict
diff --git a/tests/handlers/test_register.py b/tests/handlers/test_register.py
index 001761f2b1..010e65829e 100644
--- a/tests/handlers/test_register.py
+++ b/tests/handlers/test_register.py
@@ -21,7 +21,7 @@ from synapse.api.constants import UserTypes
 from synapse.api.errors import ResourceLimitError, SynapseError
 from synapse.handlers.register import RegistrationHandler
 from synapse.types import RoomAlias, UserID, create_requester
-from synapse.api.urls import ConsentURIBuilder
+
 from tests.utils import setup_test_homeserver
 
 from .. import unittest
@@ -190,27 +190,29 @@ class RegistrationTestCase(unittest.TestCase):
         """Test to ensure that the first user is not auto-joined to a room if
         they have not given general consent.
         """
-        self.hs.config.user_consent_at_registration = True
-        self.hs.config.block_events_without_consent_error = "Error"
 
         # Given:-
         #    * a user must give consent,
         #    * they have not given that consent
         #    * The server is configured to auto-join to a room
         # (and autocreate if necessary)
+
         event_creation_handler = self.hs.get_event_creation_handler()
-        event_creation_handler._block_events_without_consent_error = (
-            self.hs.config.block_events_without_consent_error
-        )
+        # (Messing with the internals of event_creation_handler is fragile
+        # but can't see a better way to do this. One option could be to subclass
+        # the test with custom config.)
+        event_creation_handler._block_events_without_consent_error = ("Error")
         event_creation_handler._consent_uri_builder = Mock()
         room_alias_str = "#room:test"
         self.hs.config.auto_join_rooms = [room_alias_str]
 
-        # When the user is registered, and post consent actions are called
+        # When:-
+        #   * the user is registered and post consent actions are called
         res = yield self.handler.register(localpart='jeff')
         yield self.handler.post_consent_actions(res[0])
 
-        # Ensure that they have not been joined to the room
+        # Then:-
+        #   * Ensure that they have not been joined to the room
         rooms = yield self.store.get_rooms_for_user(res[0])
         self.assertEqual(len(rooms), 0)