diff --git a/libs/partners/openai/langchain_openai/chat_models/base.py b/libs/partners/openai/langchain_openai/chat_models/base.py
index 8a1a63bbcdbfb..9d6c1996423d8 100644
--- a/libs/partners/openai/langchain_openai/chat_models/base.py
+++ b/libs/partners/openai/langchain_openai/chat_models/base.py
@@ -977,7 +977,7 @@ def _should_stream(
             # TODO: Add support for streaming with Pydantic response_format.
             warnings.warn("Streaming with Pydantic response_format not yet supported.")
             return False
-        if self.model_name.startswith("o1"):
+        if self.model_name is not None and self.model_name.startswith("o1"):
             # TODO: Add support for streaming with o1 once supported.
             return False