diff --git a/deck/chat.py b/deck/chat.py
index be24bc8..a0b62c7 100644
--- a/deck/chat.py
+++ b/deck/chat.py
@@ -25,6 +25,7 @@ class DeckChat:
     Register a new handler inside the chat instance.
     The handler accepts two parameters: a message and a state object,
     and returns the response and the new state object.
+    If the returned state object is None, then the chat loop exits.
     Non-command handler is registered under the 'default' command.
     """
     cmd = command.strip().lower()