diff --git a/src/smolagents/cli.py b/src/smolagents/cli.py
index 6d5c07020..7d93a3b7a 100644
--- a/src/smolagents/cli.py
+++ b/src/smolagents/cli.py
@@ -79,7 +79,7 @@ def parse_arguments(description):
     return parser.parse_args()
 
 
-def load_model(model_type: str, model_id: str, api_base: str | None, api_key: str | None) -> Model:
+def load_model(model_type: str, model_id: str, api_base: str | None = None, api_key: str | None = None) -> Model:
     if model_type == "OpenAIServerModel":
         return OpenAIServerModel(
             api_key=api_key or os.getenv("FIREWORKS_API_KEY"),