diff --git a/pkg-py/src/shinychat/_chat.py b/pkg-py/src/shinychat/_chat.py
index 9443993..30f7e31 100644
--- a/pkg-py/src/shinychat/_chat.py
+++ b/pkg-py/src/shinychat/_chat.py
@@ -1603,7 +1603,7 @@ class ChatExpress(Chat):
     def ui(
         self,
         *,
-        messages: Optional[Sequence[str | ChatMessageDict]] = None,
+        messages: Optional[Sequence[TagChild | ChatMessageDict]] = None,
         placeholder: str = "Enter a message...",
         width: CssUnit = "min(680px, 100%)",
         height: CssUnit = "auto",