diff --git a/include/layer/spline.h b/include/layer/spline.h
index 59646bc..09fc488 100644
--- a/include/layer/spline.h
+++ b/include/layer/spline.h
@@ -875,7 +875,7 @@ Scalar eval2D(const Scalar *nodes1, size_t size1, const Scalar *nodes2,
             if (wxy == 0)
                 continue;
 
-            ssize_t pos = (offset[1] + y) * size1 + offset[0] + x;
+            ssize_t pos = (offset[1] + yi) * size1 + offset[0] + xi;
             result += values[pos] * wxy;
         }
     }