diff --git a/deepof/train_utils.py b/deepof/train_utils.py
index 017a390e281f8ea17c0d1e0d361b388a7bfb99b3..5f2c6e97e15717f1619cff827438033ae898d111 100644
--- a/deepof/train_utils.py
+++ b/deepof/train_utils.py
@@ -103,7 +103,7 @@ def get_callbacks(
     run_ID = "{}{}{}{}{}{}{}{}{}{}{}{}{}".format(
         ("GMVAE" if variational else "AE"),
         ("_input_type={}".format(input_type) if input_type else "coords"),
-        ("_window_size={}", format(X_train.shape[1])),
+        ("_window_size={}".format(X_train.shape[1])),
         ("_NextSeqPred={}".format(next_sequence_prediction) if variational else ""),
         ("_PhenoPred={}".format(phenotype_prediction) if variational else ""),
         ("_RuleBasedPred={}".format(rule_based_prediction) if variational else ""),