diff --git a/tf_base_model.py b/tf_base_model.py
index b9e87bb8..08cb7e80 100644
--- a/tf_base_model.py
+++ b/tf_base_model.py
@@ -160,7 +160,7 @@ def fit(self):
                     val_feed_dict.update({self.is_training: False})
 
                 results = self.session.run(
-                    fetches=[self.loss] + self.metrics.values(),
+                    fetches=[self.loss] + list(self.metrics.values()),
                     feed_dict=val_feed_dict
                 )
                 val_loss = results[0]