diff --git a/synapse/events/spamcheck.py b/synapse/events/spamcheck.py
index 458be77083..b404cf6f84 100644
--- a/synapse/events/spamcheck.py
+++ b/synapse/events/spamcheck.py
@@ -45,7 +45,10 @@ CHECK_EVENT_FOR_SPAM_CALLBACK = Callable[
     Awaitable[Union[bool, str]],
 ]
 # FIXME: Callback signature differs from mainline
-USER_MAY_INVITE_CALLBACK = Callable[[str, str, str, str, bool, bool], Awaitable[bool]]
+USER_MAY_INVITE_CALLBACK = Callable[
+    [str, Optional[str], Optional[dict], str, bool, bool],
+    Awaitable[bool]
+]
 # FIXME: Callback signature differs from mainline
 USER_MAY_CREATE_ROOM_CALLBACK = Callable[
     [str, List[str], List[dict], bool], Awaitable[bool]
diff --git a/synapse/http/servlet.py b/synapse/http/servlet.py
index a12fa30bfd..3688a7f5e7 100644
--- a/synapse/http/servlet.py
+++ b/synapse/http/servlet.py
@@ -22,7 +22,7 @@ from typing import (
     Optional,
     Sequence,
     Tuple,
-    overload,
+    overload, Union,
 )
 
 from typing_extensions import Literal
@@ -630,7 +630,7 @@ def parse_json_object_from_request(
     return content
 
 
-def assert_params_in_dict(body: JsonDict, required: Iterable[str]) -> None:
+def assert_params_in_dict(body: JsonDict, required: Iterable[Union[str, bytes]]) -> None:
     absent = []
     for k in required:
         if k not in body:
diff --git a/synapse/rest/client/account.py b/synapse/rest/client/account.py
index d5ef51a8c4..69e3083fea 100644
--- a/synapse/rest/client/account.py
+++ b/synapse/rest/client/account.py
@@ -17,7 +17,7 @@ import logging
 import random
 import re
 from http import HTTPStatus
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Optional
 from urllib.parse import urlparse
 
 from synapse.api.constants import LoginType
@@ -692,7 +692,10 @@ class ThreepidRestServlet(RestServlet):
             # This makes the API entirely change shape when we have an AS token;
             # it really should be an entirely separate API - perhaps
             # /account/3pid/replicate or something.
-            threepid = body.get("threepid")
+            threepid: Optional[dict] = body.get("threepid")
+
+            if not threepid:
+                raise SynapseError(400, "Missing param 'threepid'")
 
             await self.auth_handler.add_threepid(
                 user_id,
diff --git a/tests/storage/test_profile.py b/tests/storage/test_profile.py
index 33ef510b21..acbb9a57c4 100644
--- a/tests/storage/test_profile.py
+++ b/tests/storage/test_profile.py
@@ -41,7 +41,7 @@ class ProfileStoreTestCase(unittest.HomeserverTestCase):
 
         # test set to None
         self.get_success(
-            self.store.set_profile_displayname(self.u_frank.localpart, None)
+            self.store.set_profile_displayname(self.u_frank.localpart, None, 1)
         )
 
         self.assertIsNone(