diff --git a/python/sglang/srt/managers/router/model_rpc.py b/python/sglang/srt/managers/router/model_rpc.py
index c0c46ca17..4d77eed03 100644
--- a/python/sglang/srt/managers/router/model_rpc.py
+++ b/python/sglang/srt/managers/router/model_rpc.py
@@ -229,6 +229,7 @@ class ModelRpcServer(rpyc.Service):
         req.sampling_params.max_new_tokens = min(
             req.sampling_params.max_new_tokens,
             self.model_config.context_len - 1 - len(req.input_ids),
+            self.max_total_num_token - 128 - len(req.input_ids),
         )
         self.forward_queue.append(req)