diff --git a/cyclegan/models/test_model.py b/cyclegan/models/test_model.py
index 4c3be38..915f330 100644
--- a/cyclegan/models/test_model.py
+++ b/cyclegan/models/test_model.py
@@ -77,7 +77,7 @@ class TestModel(BaseModel):
         pgd_attack = attacks.LinfPGDAttack(model=self.netG)
         black = np.zeros((1, 3, image.size(2), image.size(3)))
         black = torch.FloatTensor(black).cuda()
-        input_adv, perturb = pgd_attack.perturb(image, black)      
+        input_adv, perturb = pgd_attack.perturb(image, image)      
         
         return input_adv, perturb
 
diff --git a/cyclegan/util/attacks.py b/cyclegan/util/attacks.py
index c51c813..cd2d38a 100644
--- a/cyclegan/util/attacks.py
+++ b/cyclegan/util/attacks.py
@@ -27,7 +27,7 @@ class LinfPGDAttack(object):
             output = self.model(X)
 
             self.model.zero_grad()
-            loss = -self.loss_fn(output, y)
+            loss = self.loss_fn(output, y)
             loss.backward()
             grad = X.grad