diff --git a/example/ck_tile/18_hstu_attention/hstu_block_masking.hpp b/example/ck_tile/18_hstu_attention/hstu_block_masking.hpp
index f622370017..b60ff806b4 100644
--- a/example/ck_tile/18_hstu_attention/hstu_block_masking.hpp
+++ b/example/ck_tile/18_hstu_attention/hstu_block_masking.hpp
@@ -186,7 +186,7 @@ struct HstuCrossAttentionBlockMaskWithLocal
         };
     }
 
-    CK_TILE_HOST_DEVICE bool IsTokenPairInsideMask(int row, int col)
+    CK_TILE_HOST_DEVICE bool IsTokenPairInsideMask(int row, int col) const
     {
         int row_id;
         int col_id;
@@ -425,7 +425,7 @@ struct HstuSelfAttentionBlockMaskWithLocal
         };
     }
 
-    CK_TILE_HOST_DEVICE bool IsTokenPairInsideMask(int row, int col)
+    CK_TILE_HOST_DEVICE bool IsTokenPairInsideMask(int row, int col) const
     {
         int row_id;
         int col_id;
@@ -577,7 +577,7 @@ struct HstuCrossAttentionBlockMaskNoLocal
         };
     }
 
-    CK_TILE_HOST_DEVICE bool IsTokenPairInsideMask(int row, int col)
+    CK_TILE_HOST_DEVICE bool IsTokenPairInsideMask(int row, int col) const
     {
         int row_id;
         int col_id;
@@ -713,7 +713,7 @@ struct HstuSelfAttentionBlockMaskNoLocal
         };
     }
 
-    CK_TILE_HOST_DEVICE bool IsTokenPairInsideMask(int row, int col)
+    CK_TILE_HOST_DEVICE bool IsTokenPairInsideMask(int row, int col) const
     {
         int row_id;
         int col_id;