1 files changed, 3 insertions, 0 deletions
diff --git a/synapse/rest/admin/users.py b/synapse/rest/admin/users.py
index aaa56a7024..309bd2771b 100644
--- a/synapse/rest/admin/users.py
+++ b/synapse/rest/admin/users.py
@@ -833,6 +833,9 @@ class UserMediaRestServlet(RestServlet):
     async def on_GET(
         self, request: SynapseRequest, user_id: str
     ) -> Tuple[int, JsonDict]:
+        # This will always be set by the time Twisted calls us.
+        assert request.args is not None
+
         await assert_requester_is_admin(self.auth, request)
 
         if not self.is_mine(UserID.from_string(user_id)):