diff --git a/changelog.d/8664.misc b/changelog.d/8664.misc
new file mode 100644
index 0000000000000000000000000000000000000000..278cf53adc46e0708577e0455537c4a4c1e12599
--- /dev/null
+++ b/changelog.d/8664.misc
@@ -0,0 +1 @@
+Tell Black to format code for Python 3.5.
diff --git a/pyproject.toml b/pyproject.toml
index db4a2e41e439435008a9749e73a5dbf132cf75d9..cd880d4e39bfb52ab8d1ba4811fed7fc00130a49 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -35,7 +35,7 @@
         showcontent = true
 
 [tool.black]
-target-version = ['py34']
+target-version = ['py35']
 exclude = '''
 
 (
diff --git a/synapse/http/client.py b/synapse/http/client.py
index 8324632cb6251ac0582770d5b378f7ec5951149a..f409368802c5fa5bd84ffb453f45d9034ccb7518 100644
--- a/synapse/http/client.py
+++ b/synapse/http/client.py
@@ -359,7 +359,7 @@ class SimpleHttpClient:
                     agent=self.agent,
                     data=body_producer,
                     headers=headers,
-                    **self._extra_treq_args
+                    **self._extra_treq_args,
                 )  # type: defer.Deferred
 
                 # we use our own timeout mechanism rather than treq's as a workaround
diff --git a/synapse/storage/database.py b/synapse/storage/database.py
index 0217e631085a992f999c220761fccf9b20c11bca..a0572b295239f1d76aad51149556a65cbec08fb4 100644
--- a/synapse/storage/database.py
+++ b/synapse/storage/database.py
@@ -94,7 +94,7 @@ def make_pool(
         cp_openfun=lambda conn: engine.on_new_connection(
             LoggingDatabaseConnection(conn, engine, "on_new_connection")
         ),
-        **db_config.config.get("args", {})
+        **db_config.config.get("args", {}),
     )
 
 
@@ -632,7 +632,7 @@ class DatabasePool:
                 func,
                 *args,
                 db_autocommit=db_autocommit,
-                **kwargs
+                **kwargs,
             )
 
             for after_callback, after_args, after_kwargs in after_callbacks:
diff --git a/synapse/util/retryutils.py b/synapse/util/retryutils.py
index a5cc9d0551869542f9eb4a4fb4c02144fe0db40e..4ab379e429986d7977c95e8cbaf0dca98c98494b 100644
--- a/synapse/util/retryutils.py
+++ b/synapse/util/retryutils.py
@@ -110,7 +110,7 @@ async def get_retry_limiter(destination, clock, store, ignore_backoff=False, **k
         failure_ts,
         retry_interval,
         backoff_on_failure=backoff_on_failure,
-        **kwargs
+        **kwargs,
     )
 
 
diff --git a/tests/replication/_base.py b/tests/replication/_base.py
index 093e2faac7bf807afd74e269c07116786054e496..f1e53f33cd918b4816df467ca7b3cf6c7ef71530 100644
--- a/tests/replication/_base.py
+++ b/tests/replication/_base.py
@@ -269,7 +269,7 @@ class BaseMultiWorkerStreamTestCase(unittest.HomeserverTestCase):
             homeserver_to_use=GenericWorkerServer,
             config=config,
             reactor=self.reactor,
-            **kwargs
+            **kwargs,
         )
 
         # If the instance is in the `instance_map` config then workers may try
diff --git a/tests/replication/tcp/streams/test_events.py b/tests/replication/tcp/streams/test_events.py
index c9998e88e6b7020d78b6d1916ce28e29716c4109..bad0df08cf0293fc07452c657448a6bdafb0323c 100644
--- a/tests/replication/tcp/streams/test_events.py
+++ b/tests/replication/tcp/streams/test_events.py
@@ -449,7 +449,7 @@ class EventsStreamTestCase(BaseStreamTestCase):
                 sender=sender,
                 type="test_event",
                 content={"body": body},
-                **kwargs
+                **kwargs,
             )
         )
 
diff --git a/tests/server.py b/tests/server.py
index 4d33b8409736159575fca392478e083656224f25..ea9c22bc51c62308dfa6ac687c1b60e490df60c0 100644
--- a/tests/server.py
+++ b/tests/server.py
@@ -380,7 +380,7 @@ def setup_test_homeserver(cleanup_func, *args, **kwargs):
                 pool._runWithConnection,
                 func,
                 *args,
-                **kwargs
+                **kwargs,
             )
 
         def runInteraction(interaction, *args, **kwargs):
@@ -390,7 +390,7 @@ def setup_test_homeserver(cleanup_func, *args, **kwargs):
                 pool._runInteraction,
                 interaction,
                 *args,
-                **kwargs
+                **kwargs,
             )
 
         pool.runWithConnection = runWithConnection
diff --git a/tests/storage/test_client_ips.py b/tests/storage/test_client_ips.py
index 755c70db314280ce27837debc1070f7c87bc0d66..e96ca1c8cab9e465f5ed563d5f4a72395fb95741 100644
--- a/tests/storage/test_client_ips.py
+++ b/tests/storage/test_client_ips.py
@@ -412,7 +412,7 @@ class ClientIpAuthTestCase(unittest.HomeserverTestCase):
             "GET",
             "/_matrix/client/r0/admin/users/" + self.user_id,
             access_token=access_token,
-            **make_request_args
+            **make_request_args,
         )
         request.requestHeaders.addRawHeader(b"User-Agent", b"Mozzila pizza")
 
diff --git a/tests/test_utils/event_injection.py b/tests/test_utils/event_injection.py
index e93aa84405f5ed2a4f7506411db1432d4222a49a..c3c4a93e1f9b343eb18df283426322805a297b1e 100644
--- a/tests/test_utils/event_injection.py
+++ b/tests/test_utils/event_injection.py
@@ -50,7 +50,7 @@ async def inject_member_event(
         sender=sender,
         state_key=target,
         content=content,
-        **kwargs
+        **kwargs,
     )