diff --git a/scabha/cargo.py b/scabha/cargo.py
index ed04aa07..ba85e736 100644
--- a/scabha/cargo.py
+++ b/scabha/cargo.py
@@ -2,7 +2,7 @@
 import re, importlib, sys
 from collections import OrderedDict
 from enum import Enum, IntEnum
-from dataclasses import dataclass
+from dataclasses import dataclass, field
 from omegaconf import MISSING, ListConfig, DictConfig, OmegaConf
 
 import rich.box
@@ -141,7 +141,7 @@ class Parameter(object):
     nom_de_guerre: Optional[str] = None
 
     # policies object, specifying a non-default way to handle this parameter
-    policies: ParameterPolicies = ParameterPolicies()
+    policies: ParameterPolicies = field(default_factory=ParameterPolicies)
 
     # Parameter category, purely cosmetic, used for generating help and debug messages.
     # Assigned automatically if None, but a schema may explicitly mark parameters as e.g.
diff --git a/scabha/schema_utils.py b/scabha/schema_utils.py
index 68f5bc16..9cf51de5 100644
--- a/scabha/schema_utils.py
+++ b/scabha/schema_utils.py
@@ -109,7 +109,7 @@ def nested_schema_to_dataclass(nested: Dict[str, Dict], class_name: str, bases=(
         dcls = schema_to_dataclass(content, f"{class_name}_{section}",
                                     bases=section_bases, post_init=post_init_map.get(section))
 
-        fields.append((section, dcls, field(default=dcls())))
+        fields.append((section, dcls, field(default_factory=dcls)))
 
     # return the outer dataclass
     return make_dataclass(class_name, fields, bases=bases)