diff --git a/force_bdss/data_sources/base_data_source_model.py b/force_bdss/data_sources/base_data_source_model.py
index 0b7204565a7fce6da7af159ff23538b1ab1b6a78..d88d3adff6f7938b163a3369a38612864a9a2132 100644
--- a/force_bdss/data_sources/base_data_source_model.py
+++ b/force_bdss/data_sources/base_data_source_model.py
@@ -1,8 +1,8 @@
 import abc
-import six
+from traits.api import ABCHasStrictTraits
 
 
-class BaseDataSourceModel(six.with_metaclass(abc.ABCMeta)):
+class BaseDataSourceModel(ABCHasStrictTraits):
     @classmethod
     @abc.abstractmethod
     def from_json(self, model_data):
diff --git a/force_bdss/kpi/base_kpi_calculator_model.py b/force_bdss/kpi/base_kpi_calculator_model.py
index 38e1acb89dd6388ca2796de85a2da73d6f4915e4..9489b9b89ded2d98442b5f72052e2666673952a7 100644
--- a/force_bdss/kpi/base_kpi_calculator_model.py
+++ b/force_bdss/kpi/base_kpi_calculator_model.py
@@ -1,8 +1,8 @@
-import six
 import abc
+from traits.has_traits import ABCHasStrictTraits
 
 
-class BaseKPICalculatorModel(six.with_metaclass(abc.ABCMeta)):
+class BaseKPICalculatorModel(ABCHasStrictTraits):
     @classmethod
     @abc.abstractmethod
     def from_json(self, model_data):
diff --git a/force_bdss/mco/base_mco_model.py b/force_bdss/mco/base_mco_model.py
index db861acd4f10b47c7f2f784f20ce7013df86dbb6..3bf128cfb0f7132eed980a92cd8d39770233a097 100644
--- a/force_bdss/mco/base_mco_model.py
+++ b/force_bdss/mco/base_mco_model.py
@@ -1,8 +1,8 @@
 import abc
-import six
+from traits.api import ABCHasStrictTraits
 
 
-class BaseMCOModel(six.with_metaclass(abc.ABCMeta)):
+class BaseMCOModel(ABCHasStrictTraits):
     @classmethod
     @abc.abstractmethod
     def from_json(self, model_data):