diff --git a/src/llamafactory/api/protocol.py b/src/llamafactory/api/protocol.py
index a69132ea..c6fe6f75 100644
--- a/src/llamafactory/api/protocol.py
+++ b/src/llamafactory/api/protocol.py
@@ -96,7 +96,7 @@ class ChatCompletionRequest(BaseModel):
     model: str
     messages: List[ChatMessage]
     tools: Optional[List[FunctionAvailable]] = None
-    do_sample: bool = True
+    do_sample: Optional[bool] = None
     temperature: Optional[float] = None
     top_p: Optional[float] = None
     n: int = 1
diff --git a/src/llamafactory/chat/hf_engine.py b/src/llamafactory/chat/hf_engine.py
index 22a24339..6e728c2b 100644
--- a/src/llamafactory/chat/hf_engine.py
+++ b/src/llamafactory/chat/hf_engine.py
@@ -119,7 +119,7 @@ class HuggingfaceEngine(BaseEngine):
         stop: Optional[Union[str, List[str]]] = input_kwargs.pop("stop", None)
 
         if stop is not None:
-            logger.warning("Stop parameter is not supported in Huggingface engine yet.")
+            logger.warning("Stop parameter is not supported by the huggingface engine yet.")
 
         generating_args = generating_args.copy()
         generating_args.update(