diff --git a/src/engine_args.py b/src/engine_args.py
index d1bc532..64cd75e 100644
--- a/src/engine_args.py
+++ b/src/engine_args.py
@@ -91,8 +91,10 @@ DEFAULT_ARGS = {
     "disable_logprobs_during_spec_decoding": os.getenv('DISABLE_LOGPROBS_DURING_SPEC_DECODING', None),
     "otlp_traces_endpoint": os.getenv('OTLP_TRACES_ENDPOINT', None),
     "use_v2_block_manager": os.getenv('USE_V2_BLOCK_MANAGER', 'true'),
-    "limit_mm_per_prompt": convert_limit_mm_per_prompt(os.getenv('LIMIT_MM_PER_PROMPT', 'image=1,video=0')),
 }
+limit_mm_env = os.getenv('LIMIT_MM_PER_PROMPT')
+if limit_mm_env is not None:
+    DEFAULT_ARGS["limit_mm_per_prompt"] = convert_limit_mm_per_prompt(limit_mm_env)
 
 def match_vllm_args(args):
     """Rename args to match vllm by: