diff --git a/swarms/agents/utils/llm.py b/swarms/agents/utils/llm.py
index b28d932b..a9fdb265 100644
--- a/swarms/agents/utils/llm.py
+++ b/swarms/agents/utils/llm.py
@@ -139,7 +139,7 @@ class ChatOpenAI(BaseChatModel, BaseModel):
     """
 
     client: Any  #: :meta private:
-    model_name: str = os.environ["MODEL_NAME"]
+    model_name: str = os.environ["MODEL_NAME"] or 'gpt-4'
     """Model name to use."""
     model_kwargs: Dict[str, Any] = Field(default_factory=dict)
     """Holds any model parameters valid for `create` call not explicitly specified."""