diff --git a/example/ck_tile/18_hstu_attention/test_pytorch_hstu_mask.py b/example/ck_tile/18_hstu_attention/test_pytorch_hstu_mask.py
index 35e5f427f2..6ba1955c27 100644
--- a/example/ck_tile/18_hstu_attention/test_pytorch_hstu_mask.py
+++ b/example/ck_tile/18_hstu_attention/test_pytorch_hstu_mask.py
@@ -40,7 +40,7 @@ def get_valid_attn_mask(
 
     ## 1) for token pair in [seqlen-num_target, N) x [seqlen-num_target, N), row_col_dist is 0
     ## 2) for token pair in [seqlen-num-target, N) x [0, seqlen-num_target), row_col_dist > 0
-    ## 3) for token_pair in [0, seq-num_target) x [seqlen-num_target, N). row_col_dist < 0 if causal, else row_col_dist > 0 
+    ## 3) for token_pair in [0, seqlen-num_target) x [seqlen-num_target, N). row_col_dist < 0 if causal, else row_col_dist > 0
     valid_attn_mask = torch.logical_or(valid_attn_mask, row_col_dist > 0)
     if max_attn_len > 0:
         if min_full_attn_seq_len > 0: