diff --git a/talk.py b/talk.py
index e524a54..2cc3683 100644
--- a/talk.py
+++ b/talk.py
@@ -266,10 +266,7 @@ class Talk:
 
         try:
             return (openai.chat.completions.create (
-                        model    = ('gpt-4o'
-                                    if any (type (e['content']) is list
-                                            for e in messages)
-                                    else 'gpt-3.5-turbo'),
+                        model    = 'gpt-6-luna',
                         messages = messages)
                     .choices[0].message)
         except: