diff --git a/synapse/federation/send_queue.py b/synapse/federation/send_queue.py
index 7e52a55eda913b3f4a343a9cf65f9e666b044a8a..19cb757accb00df233e26da7b4021ca715edd084 100644
--- a/synapse/federation/send_queue.py
+++ b/synapse/federation/send_queue.py
@@ -191,9 +191,15 @@ class FederationRemoteSendQueue(object):
         self.notifier.on_new_replication_data()
 
     def send_presence(self, states):
-        """As per TransactionQueue"""
+        """As per TransactionQueue
+
+        Args:
+            states (list(UserPresenceState))
+        """
         pos = self._next_pos()
 
+        # We only want to send presence for our own users, so lets always just
+        # filter here just in case.
         local_states = filter(lambda s: self.is_mine_id(s.user_id), states)
 
         self.presence_map.update({state.user_id: state for state in local_states})
diff --git a/synapse/federation/transaction_queue.py b/synapse/federation/transaction_queue.py
index 08ceda31a6e9bd7555667b49b7f0e46443ecd0d5..260a4722557bec3f36f2b5e6c7084acf823e15fe 100644
--- a/synapse/federation/transaction_queue.py
+++ b/synapse/federation/transaction_queue.py
@@ -251,6 +251,8 @@ class TransactionQueue(object):
 
         # First we queue up the new presence by user ID, so multiple presence
         # updates in quick successtion are correctly handled
+        # We only want to send presence for our own users, so lets always just
+        # filter here just in case.
         self.pending_presence.update({
             state.user_id: state for state in states
             if self.is_mine_id(state.user_id)