diff --git a/src/callbacks.py b/src/callbacks.py
index e8cb863f8..86aa98915 100644
--- a/src/callbacks.py
+++ b/src/callbacks.py
@@ -80,7 +80,7 @@ def _addressed(irc, msg, prefixChars=None, nicks=None,
                 payload = payload[len(prefixString):].lstrip()
         return payload
 
-    assert msg.command in ('PRIVMSG', 'TAGMSG')
+    assert msg.command in ('PRIVMSG', 'TAGMSG'), msg.command
     target = msg.channel or msg.args[0]
     if not payload:
         payload = msg.args[1]