diff --git a/vall_e/engines/__init__.py b/vall_e/engines/__init__.py
index 955f50a..2a28f1d 100755
--- a/vall_e/engines/__init__.py
+++ b/vall_e/engines/__init__.py
@@ -146,7 +146,7 @@ def load_engines(training=True, **model_kwargs):
 			elif cfg.hyperparameters.optimizer.lower() == "adagrad":
 				optimizer_class = ml.Adagrad
 			elif cfg.hyperparameters.optimizer.lower() == "muon":
-				optimizer = ml.Muon
+				optimizer_class = ml.Muon
 
 				muon_params = [ param for name, param in model.model.named_parameters() if param.ndim >= 2 ]
 				adamw_params = [ param for name, param in model.model.named_parameters() if param.ndim < 2 ]