diff --git a/packages/jupyter-ai/src/components/chat-messages.tsx b/packages/jupyter-ai/src/components/chat-messages.tsx
index c3fc0921a..aaae93a18 100644
--- a/packages/jupyter-ai/src/components/chat-messages.tsx
+++ b/packages/jupyter-ai/src/components/chat-messages.tsx
@@ -49,11 +49,11 @@ function sortMessages(
      */
 
     const aOriginTimestamp =
-      a.type === 'agent' && a.reply_to in timestampsById
+      'reply_to' in a && a.reply_to in timestampsById
         ? timestampsById[a.reply_to]
         : a.time;
     const bOriginTimestamp =
-      b.type === 'agent' && b.reply_to in timestampsById
+      'reply_to' in b && b.reply_to in timestampsById
         ? timestampsById[b.reply_to]
         : b.time;