diff --git a/mmp/a1/tensors.py b/mmp/a1/tensors.py
index 72e1c29..4c926c6 100644
--- a/mmp/a1/tensors.py
+++ b/mmp/a1/tensors.py
@@ -14,4 +14,4 @@ def mask(foreground: torch.Tensor, background: torch.Tensor, mask_tensor: torch.
 
 
 def add_matrix_vector(matrix: torch.Tensor, vector: torch.Tensor):
-    return matrix.add(vector)
+    return matrix + vector.unsqueeze(1)