diff --git a/comfy/ldm/lightricks/vae/pixel_norm.py b/comfy/ldm/lightricks/vae/pixel_norm.py
index 9bc3ea60e..0edf06927 100644
--- a/comfy/ldm/lightricks/vae/pixel_norm.py
+++ b/comfy/ldm/lightricks/vae/pixel_norm.py
@@ -9,4 +9,5 @@ class PixelNorm(nn.Module):
         self.eps = eps
 
     def forward(self, x):
-        return x / torch.sqrt(torch.mean(x**2, dim=self.dim, keepdim=True) + self.eps)
+        mean_square = torch.mean(x * x, dim=self.dim, keepdim=True) + self.eps
+        return x * torch.rsqrt(mean_square)