diff --git a/libs/partners/openai/langchain_openai/chat_models/base.py b/libs/partners/openai/langchain_openai/chat_models/base.py
index fdc5327218e..cfb479906f1 100644
--- a/libs/partners/openai/langchain_openai/chat_models/base.py
+++ b/libs/partners/openai/langchain_openai/chat_models/base.py
@@ -1873,7 +1873,8 @@ class BaseChatOpenAI(BaseChatModel):
             
             tool_name = convert_to_openai_tool(schema)["function"]["name"]
             base_url = (
-                getattr(self, "openai_api_base", "") or getattr(self, "api_base", "") or ""
+                getattr(self, "openai_api_base", "")
+                or getattr(self, "api_base", "") or ""
             ).lower()
             # The Azure-Hosted Models routes to this function
             # so we need to set the tool_choice to required