diff --git a/library/config_util.py b/library/config_util.py
index 47a3ac826..e62bfb895 100644
--- a/library/config_util.py
+++ b/library/config_util.py
@@ -283,7 +283,9 @@ def sanitize_argparse_namespace(self, argparse_namespace: argparse.Namespace) ->
   def __merge_dict(*dict_list: dict) -> dict:
     merged = {}
     for schema in dict_list:
-      merged |= schema
+      # merged |= schema
+      for k, v in schema.items():
+        merged[k] = v
     return merged