diff --git a/src/llamafactory/chat/vllm_engine.py b/src/llamafactory/chat/vllm_engine.py
index f1a6e9d8..c696978e 100644
--- a/src/llamafactory/chat/vllm_engine.py
+++ b/src/llamafactory/chat/vllm_engine.py
@@ -83,7 +83,8 @@ class VllmEngine(BaseEngine):
             "enable_lora": model_args.adapter_name_or_path is not None,
             "max_lora_rank": model_args.vllm_max_lora_rank,
         }
-        engine_args.update(model_args.vllm_config)
+        if isinstance(model_args.vllm_config, dict):
+            engine_args.update(model_args.vllm_config)
 
         if getattr(config, "is_yi_vl_derived_model", None):
             import vllm.model_executor.models.llava