diff --git a/FrEIA/modules/all_in_one_block.py b/FrEIA/modules/all_in_one_block.py
index 07bb1e6..3ad846e 100644
--- a/FrEIA/modules/all_in_one_block.py
+++ b/FrEIA/modules/all_in_one_block.py
@@ -223,12 +223,12 @@ def _affine(self, x, a, rev=False):
 
         # the entire coupling coefficient tensor is scaled down by a
         # factor of ten for stability and easier initialization.
-        a *= 0.1
+        a = a * 0.1
         ch = x.shape[1]
 
         sub_jac = self.clamp * torch.tanh(a[:, :ch]/self.clamp)
         if self.GIN:
-            sub_jac -= torch.mean(sub_jac, dim=self.sum_dims, keepdim=True)
+            sub_jac = sub_jac - torch.mean(sub_jac, dim=self.sum_dims, keepdim=True) 
 
         if not rev:
             return (x * torch.exp(sub_jac) + a[:, ch:],
@@ -279,7 +279,7 @@ def forward(self, x, c=[], rev=False, jac=True):
         # trick to get the total number of non-channel dimensions:
         # number of elements of the first channel of the first batch member
         n_pixels = x_out[0, :1].numel()
-        log_jac_det += (-1)**rev * n_pixels * global_scaling_jac
+        log_jac_det = log_jac_det + (-1)**rev * n_pixels * global_scaling_jac
 
         return (x_out,), log_jac_det