diff --git a/vllm/sequence.py b/vllm/sequence.py
index 4f0adac743c36..942cf9ecec80e 100644
--- a/vllm/sequence.py
+++ b/vllm/sequence.py
@@ -35,6 +35,9 @@ class SequenceStatus(enum.Enum):
         elif status == SequenceStatus.FINISHED_ABORTED:
             finish_reason = "abort"
         elif status == SequenceStatus.FINISHED_IGNORED:
+            # The ignored sequences are the sequences whose prompt lengths
+            # are longer than the model's length cap. Therefore, the stop
+            # reason should also be "length" as in OpenAI API.
             finish_reason = "length"
         else:
             finish_reason = None