diff --git a/ldm/models/diffusion/ddpm.py b/ldm/models/diffusion/ddpm.py
index bbedd04cf..f4e406967 100644
--- a/ldm/models/diffusion/ddpm.py
+++ b/ldm/models/diffusion/ddpm.py
@@ -160,7 +160,7 @@ def register_schedule(self, given_betas=None, beta_schedule="linear", timesteps=
             lvlb_weights = self.betas ** 2 / (
                         2 * self.posterior_variance * to_torch(alphas) * (1 - self.alphas_cumprod))
         elif self.parameterization == "x0":
-            lvlb_weights = 0.5 * np.sqrt(torch.Tensor(alphas_cumprod)) / (2. * 1 - torch.Tensor(alphas_cumprod))
+            lvlb_weights = 0.5 * np.sqrt(torch.Tensor(alphas_cumprod)) / (2. * (1. - torch.Tensor(alphas_cumprod)))
         else:
             raise NotImplementedError("mu not supported")
         # TODO how to choose this term