diff --git a/python/sglang/srt/constrained/reasoner_grammar_backend.py b/python/sglang/srt/constrained/reasoner_grammar_backend.py
index 5fe7b0c8c00a..4dc20180b593 100644
--- a/python/sglang/srt/constrained/reasoner_grammar_backend.py
+++ b/python/sglang/srt/constrained/reasoner_grammar_backend.py
@@ -99,6 +99,9 @@ def jump_and_retokenize(
             old_output_ids, new_output_ids, next_state
         )
 
+    def is_terminated(self):
+        return self.grammar.is_terminated()
+
 
 class ReasonerGrammarBackend(BaseGrammarBackend):
     def __init__(self, grammar_backend: BaseGrammarBackend, think_end_id):