diff --git a/changelog.d/239.misc b/changelog.d/239.misc
new file mode 100644
index 00000000..35759845
--- /dev/null
+++ b/changelog.d/239.misc
@@ -0,0 +1 @@
+Fix type hint errors from new upstream Twisted release.
diff --git a/sygnal/helper/proxy/connectproxyclient_twisted.py b/sygnal/helper/proxy/connectproxyclient_twisted.py
index 1c24bc47..5a4b386b 100644
--- a/sygnal/helper/proxy/connectproxyclient_twisted.py
+++ b/sygnal/helper/proxy/connectproxyclient_twisted.py
@@ -109,13 +109,14 @@ def __init__(
         self.dst_port = dst_port
         self._proxy_auth = proxy_auth
         self.wrapped_factory = wrapped_factory
-        self.on_connection = defer.Deferred()
+        self.on_connection: defer.Deferred = defer.Deferred()
 
     def startedConnecting(self, connector):
         return self.wrapped_factory.startedConnecting(connector)
 
     def buildProtocol(self, addr):
         wrapped_protocol = self.wrapped_factory.buildProtocol(addr)
+        assert wrapped_protocol is not None
 
         return HTTPConnectProtocol(
             self.dst_host,
@@ -220,7 +221,7 @@ def __init__(self, host: bytes, port: int, proxy_auth: Optional[Tuple[str, str]]
         self.host = host
         self.port = port
         self._proxy_auth = proxy_auth
-        self.on_connected = defer.Deferred()
+        self.on_connected: defer.Deferred = defer.Deferred()
 
     def connectionMade(self):
         logger.debug("Connected to proxy, sending CONNECT")
diff --git a/sygnal/utils.py b/sygnal/utils.py
index fb71e673..9d3db1dd 100644
--- a/sygnal/utils.py
+++ b/sygnal/utils.py
@@ -31,7 +31,7 @@ async def twisted_sleep(delay, twisted_reactor):
     Returns:
         a Deferred which fires in `delay` seconds.
     """
-    deferred = Deferred()
+    deferred: Deferred[None] = Deferred()
     twisted_reactor.callLater(delay, deferred.callback, None)
     await deferred
 
diff --git a/tests/test_pushgateway_api_v1.py b/tests/test_pushgateway_api_v1.py
index 6b2be88a..7c81758a 100644
--- a/tests/test_pushgateway_api_v1.py
+++ b/tests/test_pushgateway_api_v1.py
@@ -192,7 +192,7 @@ def test_overlong_requests_are_rejected(self):
 
         # connect the site to a fake transport.
         transport = StringTransport()
-        protocol = self.site.buildProtocol(IPv6Address("TCP", "::1", "2345"))
+        protocol = self.site.buildProtocol(IPv6Address("TCP", "::1", 2345))
         protocol.makeConnection(transport)
 
         protocol.dataReceived(
@@ -209,7 +209,7 @@ def test_overlong_requests_are_rejected(self):
 
         # now send an oversized request
         transport = StringTransport()
-        protocol = self.site.buildProtocol(IPv6Address("TCP", "::1", "2345"))
+        protocol = self.site.buildProtocol(IPv6Address("TCP", "::1", 2345))
         protocol.makeConnection(transport)
 
         protocol.dataReceived(