diff --git a/synapse/events/spamcheck.py b/synapse/events/spamcheck.py
index 595b1760f..dccc579ea 100644
--- a/synapse/events/spamcheck.py
+++ b/synapse/events/spamcheck.py
@@ -46,7 +46,7 @@ class SpamChecker(object):
 
         return self.spam_checker.check_event_for_spam(event)
 
-    def user_may_invite(self, userid, room_id):
+    def user_may_invite(self, inviter_userid, invitee_userid, room_id):
         """Checks if a given user may send an invite
 
         If this method returns false, the invite will be rejected.
@@ -60,7 +60,7 @@ class SpamChecker(object):
         if self.spam_checker is None:
             return True
 
-        return self.spam_checker.user_may_invite(userid, room_id)
+        return self.spam_checker.user_may_invite(inviter_userid, invitee_userid, room_id)
 
     def user_may_create_room(self, userid):
         """Checks if a given user may create a room
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index 737fe518e..8fccf8bab 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -1071,6 +1071,9 @@ class FederationHandler(BaseHandler):
         """
         event = pdu
 
+        if event.state_key is None:
+            raise SynapseError(400, "The invite event did not have a state key")
+
         is_blocked = yield self.store.is_room_blocked(event.room_id)
         if is_blocked:
             raise SynapseError(403, "This room has been blocked on this server")
@@ -1078,9 +1081,11 @@ class FederationHandler(BaseHandler):
         if self.hs.config.block_non_admin_invites:
             raise SynapseError(403, "This server does not accept room invites")
 
-        if not self.spam_checker.user_may_invite(event.sender, event.room_id):
+        if not self.spam_checker.user_may_invite(
+            event.sender, event.state_key, event.room_id,
+        ):
             raise SynapseError(
-                403, "This user is not permitted to send invites to this server"
+                403, "This user is not permitted to send invites to this server/user"
             )
 
         membership = event.content.get("membership")
@@ -1091,9 +1096,6 @@ class FederationHandler(BaseHandler):
         if sender_domain != origin:
             raise SynapseError(400, "The invite event was not from the server sending it")
 
-        if event.state_key is None:
-            raise SynapseError(400, "The invite event did not have a state key")
-
         if not self.is_mine_id(event.state_key):
             raise SynapseError(400, "The invite event must be for this server")
 
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index 37985fa1f..36a8ef8ce 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -225,7 +225,7 @@ class RoomMemberHandler(BaseHandler):
                     block_invite = True
 
                 if not self.spam_checker.user_may_invite(
-                    requester.user.to_string(), room_id,
+                    requester.user.to_string(), target.to_string(), room_id,
                 ):
                     logger.info("Blocking invite due to spam checker")
                     block_invite = True