diff --git a/vllm/engine/arg_utils.py b/vllm/engine/arg_utils.py
index 8065b609ca5b8..e49eaabe30e04 100644
--- a/vllm/engine/arg_utils.py
+++ b/vllm/engine/arg_utils.py
@@ -991,7 +991,6 @@ class EngineArgs:
         )
         lora_group.add_argument(
             "--enable-mm-lora",
-            action=argparse.BooleanOptionalAction,
             **lora_kwargs["enable_mm_lora"],
         )
         lora_group.add_argument("--max-cpu-loras", **lora_kwargs["max_cpu_loras"])