diff --git a/python/sglang/srt/entrypoints/openai/serving_chat.py b/python/sglang/srt/entrypoints/openai/serving_chat.py
index b91fee18c..ea72452e1 100644
--- a/python/sglang/srt/entrypoints/openai/serving_chat.py
+++ b/python/sglang/srt/entrypoints/openai/serving_chat.py
@@ -1,3 +1,4 @@
+import copy
 import json
 import logging
 import time
@@ -292,7 +293,7 @@ class OpenAIServingChat(OpenAIServingBase):
         image_data = conv.image_data if conv.image_data else None
         audio_data = conv.audio_data if conv.audio_data else None
         modalities = conv.modalities if conv.modalities else []
-        stop = conv.stop_str or [] if not request.ignore_eos else []
+        stop = copy.copy(conv.stop_str or [] if not request.ignore_eos else [])
 
         if request.stop:
             if isinstance(request.stop, str):