diff --git a/diffsynth/diffusion/loss.py b/diffsynth/diffusion/loss.py
index 14fdfd3be..065e58909 100644
--- a/diffsynth/diffusion/loss.py
+++ b/diffsynth/diffusion/loss.py
@@ -91,7 +91,9 @@ def align_trajectory(self, pipe: BasePipeline, timesteps_teacher, trajectory_tea
                 progress_id_teacher = torch.argmin((timesteps_teacher - pipe.scheduler.timesteps[progress_id + 1]).abs())
                 latents_ = trajectory_teacher[progress_id_teacher]
             
-            target = (latents_ - inputs_shared["latents"]) / (sigma_ - sigma)
+            denom = sigma_ - sigma
+            denom = torch.sign(denom) * torch.clamp(denom.abs(), min=1e-6)
+            target = (latents_ - inputs_shared["latents"]) / denom
             loss = loss + torch.nn.functional.mse_loss(noise_pred.float(), target.float()) * pipe.scheduler.training_weight(timestep)
         return loss