diff --git a/basic_demo/openai_api_server.py b/basic_demo/openai_api_server.py
index 3699051..bbca053 100644
--- a/basic_demo/openai_api_server.py
+++ b/basic_demo/openai_api_server.py
@@ -445,7 +445,7 @@ async def predict_stream(model_id, gen_params):
     function_name = None
     response_id = generate_id('chatcmpl-', 29)
     system_fingerprint = generate_id('fp_', 9)
-    tools = {tool['function']['name'] for tool in gen_params['tools']} if gen_params['tools'] else None
+    tools = {tool['function']['name'] for tool in gen_params['tools']} if gen_params['tools'] else {}
     async for new_response in generate_stream_glm4(gen_params):
         decoded_unicode = new_response["text"]
         delta_text = decoded_unicode[len(output):]