diff --git a/fastchat/serve/model_worker.py b/fastchat/serve/model_worker.py
index 683a78556..0899a3ac2 100644
--- a/fastchat/serve/model_worker.py
+++ b/fastchat/serve/model_worker.py
@@ -332,9 +332,7 @@ def create_model_worker():
         default=None,
         help="Overwrite the random seed for each generation.",
     )
-    parser.add_argument(
-        "--debug", type=bool, default=False, help="Print debugging messages"
-    )
+    parser.add_argument("--debug", action="store_true", help="Print debugging messages")
     parser.add_argument(
         "--ssl",
         action="store_true",