diff --git a/modules/callbacks.py b/modules/callbacks.py
index 51ecbdd7..a91c94a0 100644
--- a/modules/callbacks.py
+++ b/modules/callbacks.py
@@ -9,25 +9,30 @@ import transformers
 import modules.shared as shared
 
 
-# Copied from https://github.com/PygmalionAI/gradio-ui/
 class _SentinelTokenStoppingCriteria(transformers.StoppingCriteria):
 
     def __init__(self, sentinel_token_ids: list, starting_idx: int):
         transformers.StoppingCriteria.__init__(self)
         self.sentinel_token_ids = sentinel_token_ids
         self.starting_idx = starting_idx
+        self.shortest = min([x.shape[-1] for x in sentinel_token_ids])
 
     def __call__(self, input_ids: torch.LongTensor, _scores: torch.FloatTensor) -> bool:
         for sample in input_ids:
             trimmed_sample = sample[self.starting_idx:]
+            trimmed_len = trimmed_sample.shape[-1]
+            if trimmed_len < self.shortest:
+                continue
 
-            for i in range(len(self.sentinel_token_ids)):
-                # Can't unfold, output is still too tiny. Skip.
-                if trimmed_sample.shape[-1] < self.sentinel_token_ids[i].shape[-1]:
+            for sentinel in self.sentinel_token_ids:
+                sentinel_len = sentinel.shape[-1]
+                if trimmed_len < sentinel_len:
                     continue
-                for window in trimmed_sample.unfold(0, self.sentinel_token_ids[i].shape[-1], 1):
-                    if torch.all(torch.eq(self.sentinel_token_ids[i][0], window)):
-                        return True
+
+                window = trimmed_sample[-sentinel_len:]
+                if torch.all(torch.eq(sentinel, window)):
+                    return True
+
         return False