diff --git a/piker/brokers/ib.py b/piker/brokers/ib.py
index 2e0b92cb..e94fd561 100644
--- a/piker/brokers/ib.py
+++ b/piker/brokers/ib.py
@@ -1400,7 +1400,7 @@ async def trades_dialogue(
                 # mark msg as from "external system"
                 # TODO: probably something better then this.. and start
                 # considering multiplayer/group trades tracking
-                msg['external'] = True
+                msg.external = True
                 continue
 
             # XXX: we always serialize to a dict for msgpack