diff --git a/patch_transformer.py b/patch_transformer.py
index 9105bd15283d356a12ed7fed1d35a9c72ba14cf2..ddb3390fcafc9c17967e519295771c3792417688 100644
--- a/patch_transformer.py
+++ b/patch_transformer.py
@@ -109,9 +109,10 @@ class PatchTransformer(nn.Module):
         if obfuscate:
             max_x = adv_patch.shape[1]
             max_y = adv_patch.shape[2]
-            obfuscation_root = [int(random.random() * max_x), int(random.random() * max_y)]
             obfuscation_shape = [int(random.random() * max_obs_part * max_x),
                                  int(random.random() * max_obs_part * max_y)]
+            obfuscation_root = [int(random.random() * (max_x-obfuscation_shape[0])),
+                                int(random.random() * (max_y-obfuscation_shape[1]))]
             adv_patch[:, obfuscation_root[0]:obfuscation_root[0] + obfuscation_shape[0],
             obfuscation_root[1]:obfuscation_root[1] + obfuscation_shape[1]] = 0.001