diff --git a/dnn/src/naive/deformable_ps_roi_pooling/opr_impl.cpp b/dnn/src/naive/deformable_ps_roi_pooling/opr_impl.cpp
index 643e066689140f9ff3233cddf230ba9f42b4dec3..e8c04fa24eda7fe9c25d8276d47f9fbdf37fe655 100644
--- a/dnn/src/naive/deformable_ps_roi_pooling/opr_impl.cpp
+++ b/dnn/src/naive/deformable_ps_roi_pooling/opr_impl.cpp
@@ -293,7 +293,7 @@ void Fwd::exec(_megdnn_tensor_in data, _megdnn_tensor_in rois,
         float trans_std = param.trans_std, scale = param.spatial_scale;
 
         size_t nr_bbox = rois.layout[0];
-        size_t nr_cls = no_trans ? 1 : trans.layout[0];
+        size_t nr_cls = no_trans ? 1 : trans.layout[1] / 2;
         size_t IC = data.layout[1], IH = data.layout[2], IW = data.layout[3];
 
         const float* data_ptr = data.ptr<float>();
@@ -339,7 +339,7 @@ void Bwd::exec(_megdnn_tensor_in data, _megdnn_tensor_in rois,
         float trans_std = param.trans_std, scale = param.spatial_scale;
 
         size_t nr_bbox = rois.layout[0];
-        size_t nr_cls = no_trans ? 1 : trans.layout[0];
+        size_t nr_cls = no_trans ? 1 : trans.layout[1] / 2;
         size_t IC = data.layout[1], IH = data.layout[2], IW = data.layout[3];
 
         const float* data_ptr = data.ptr<float>();