diff --git a/python/sglang/srt/sampling/sampling_batch_info.py b/python/sglang/srt/sampling/sampling_batch_info.py
index f30f5eb63f7..61aa4de75c2 100644
--- a/python/sglang/srt/sampling/sampling_batch_info.py
+++ b/python/sglang/srt/sampling/sampling_batch_info.py
@@ -158,15 +158,15 @@ def update_regex_vocab_mask(self):
             return
 
         # find a grammar from the list
-        grammar = next(grammar for grammar in self.grammars if grammar)
+        first_grammar = next(grammar for grammar in self.grammars if grammar)
 
         # maybe we can reuse the existing mask?
-        self.vocab_mask = grammar.allocate_vocab_mask(
+        self.vocab_mask = first_grammar.allocate_vocab_mask(
             vocab_size=self.vocab_size,
             batch_size=len(self.temperatures),
             device=self.device,
         )
-        self.apply_mask = type(grammar).apply_vocab_mask  # force to use static method
+        self.apply_mask = first_grammar.apply_vocab_mask  # force to use static method
 
         # Apply the mask
         for i, grammar in enumerate(self.grammars):
@@ -174,7 +174,7 @@ def update_regex_vocab_mask(self):
                 grammar.fill_vocab_mask(self.vocab_mask, i)
 
         # Move the mask to the device if needed
-        self.vocab_mask = grammar.move_vocab_mask(self.vocab_mask, self.device)
+        self.vocab_mask = first_grammar.move_vocab_mask(self.vocab_mask, self.device)
 
     def filter_batch(self, unfinished_indices: List[int], new_indices: torch.Tensor):
         self.penalizer_orchestrator.filter(unfinished_indices, new_indices)