diff --git a/changelog.d/10253.misc b/changelog.d/10253.misc
new file mode 100644
index 000000000000..44d9217245c9
--- /dev/null
+++ b/changelog.d/10253.misc
@@ -0,0 +1 @@
+Fix type hints for computing auth events.
diff --git a/synapse/api/auth.py b/synapse/api/auth.py
index 29cf25763399..f8b068e56385 100644
--- a/synapse/api/auth.py
+++ b/synapse/api/auth.py
@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
-from typing import TYPE_CHECKING, Any, Dict, List, Optional, Tuple
+from typing import TYPE_CHECKING, Any, Dict, List, Optional, Tuple, Union
 
 import pymacaroons
 from netaddr import IPAddress
@@ -31,6 +31,7 @@
 from synapse.api.room_versions import KNOWN_ROOM_VERSIONS
 from synapse.appservice import ApplicationService
 from synapse.events import EventBase
+from synapse.events.builder import EventBuilder
 from synapse.http import get_request_user_agent
 from synapse.http.site import SynapseRequest
 from synapse.logging import opentracing as opentracing
@@ -490,7 +491,7 @@ async def is_server_admin(self, user: UserID) -> bool:
 
     def compute_auth_events(
         self,
-        event,
+        event: Union[EventBase, EventBuilder],
         current_state_ids: StateMap[str],
         for_verification: bool = False,
     ) -> List[str]:
diff --git a/synapse/event_auth.py b/synapse/event_auth.py
index 33d7c6024147..89bcf8151589 100644
--- a/synapse/event_auth.py
+++ b/synapse/event_auth.py
@@ -14,7 +14,7 @@
 # limitations under the License.
 
 import logging
-from typing import Any, Dict, List, Optional, Set, Tuple
+from typing import Any, Dict, List, Optional, Set, Tuple, Union
 
 from canonicaljson import encode_canonical_json
 from signedjson.key import decode_verify_key_bytes
@@ -29,6 +29,7 @@
     RoomVersion,
 )
 from synapse.events import EventBase
+from synapse.events.builder import EventBuilder
 from synapse.types import StateMap, UserID, get_domain_from_id
 
 logger = logging.getLogger(__name__)
@@ -724,7 +725,7 @@ def get_public_keys(invite_event: EventBase) -> List[Dict[str, Any]]:
     return public_keys
 
 
-def auth_types_for_event(event: EventBase) -> Set[Tuple[str, str]]:
+def auth_types_for_event(event: Union[EventBase, EventBuilder]) -> Set[Tuple[str, str]]:
     """Given an event, return a list of (EventType, StateKey) that may be
     needed to auth the event. The returned list may be a superset of what
     would actually be required depending on the full state of the room.