diff --git a/models/base_model.py b/models/base_model.py
index bb69a46fe..6a4e93da9 100644
--- a/models/base_model.py
+++ b/models/base_model.py
@@ -1025,7 +1025,7 @@ def optimize_parameters(self):
                     )
                 else:
                     ll = getattr(self, loss) / self.opt.train_iter_size
-                ll.backward(retain_graph=True)
+                ll.backward(retain_graph=False)
 
             loss_names = []