diff --git a/parallel_wavegan/bin/train.py b/parallel_wavegan/bin/train.py
index 5f417880..529338b9 100755
--- a/parallel_wavegan/bin/train.py
+++ b/parallel_wavegan/bin/train.py
@@ -219,6 +219,9 @@ def _train_step(self, batch):
         #    Discriminator    #
         #######################
         if self.steps > self.config["discriminator_train_start_steps"]:
+            # re-compute y_ which leads better quality
+            with torch.no_grad():
+                y_ = self.model["generator"](*x)
             # calculate discriminator loss
             p = self.model["discriminator"](y.unsqueeze(1))
             p_ = self.model["discriminator"](y_.unsqueeze(1).detach())