diff --git a/litellm/llms/openai/chat/o_series_transformation.py b/litellm/llms/openai/chat/o_series_transformation.py
index 6ef43ec5bf..0c5ee90b33 100644
--- a/litellm/llms/openai/chat/o_series_transformation.py
+++ b/litellm/llms/openai/chat/o_series_transformation.py
@@ -131,7 +131,10 @@ class OpenAIOSeriesConfig(OpenAIGPTConfig):
 
     def is_model_o_series_model(self, model: str) -> bool:
         model = model.split("/")[-1]  # could be "openai/o3" or "o3"
-        return model.startswith(("o1", "o3", "o4")) and model in litellm.open_ai_chat_completion_models
+        return (
+            len(model) > 1 and model[0] == "o" and model[1].isdigit()
+            and model in litellm.open_ai_chat_completion_models
+        )
 
     @overload
     def _transform_messages(