diff --git a/bionetgen/core/utils/utils.py b/bionetgen/core/utils/utils.py
index 7d19fd23..653bb124 100644
--- a/bionetgen/core/utils/utils.py
+++ b/bionetgen/core/utils/utils.py
@@ -104,6 +104,7 @@ def __init__(self):
             "max_agg",
             "max_iter",
             "max_stoich",
+            "check_iso",
             "TextReaction",
             "TextSpecies",
         ]