diff --git a/src/criterions/lovasz_losses.py b/src/criterions/lovasz_losses.py
index d83f292..a090f11 100644
--- a/src/criterions/lovasz_losses.py
+++ b/src/criterions/lovasz_losses.py
@@ -23,7 +23,7 @@ def lovasz_grad(gt_sorted):
     p = len(gt_sorted)
     gts = gt_sorted.sum()
     intersection = gts.float() - gt_sorted.float().cumsum(0)
-    union = gts.float() + (1 - gt_sorted).float().cumsum(0)
+    union = gts.float() + (~(gt_sorted)).float().cumsum(0)
     jaccard = 1. - intersection / union
     if p > 1:  # cover 1-pixel case
         jaccard[1:p] = jaccard[1:p] - jaccard[0:-1]