diff --git a/force_bdss/data_sources/base_data_source_model.py b/force_bdss/data_sources/base_data_source_model.py
index b34902074729b21ac413f71a3e279ca9828e3b44..0b7204565a7fce6da7af159ff23538b1ab1b6a78 100644
--- a/force_bdss/data_sources/base_data_source_model.py
+++ b/force_bdss/data_sources/base_data_source_model.py
@@ -3,6 +3,7 @@ import six
 
 
 class BaseDataSourceModel(six.with_metaclass(abc.ABCMeta)):
-    @abc.abstractclassmethod
+    @classmethod
+    @abc.abstractmethod
     def from_json(self, model_data):
         pass
diff --git a/force_bdss/kpi/base_kpi_calculator_model.py b/force_bdss/kpi/base_kpi_calculator_model.py
index eaa289b1e954de4ccae80ae437608d64d60e3a39..38e1acb89dd6388ca2796de85a2da73d6f4915e4 100644
--- a/force_bdss/kpi/base_kpi_calculator_model.py
+++ b/force_bdss/kpi/base_kpi_calculator_model.py
@@ -3,6 +3,7 @@ import abc
 
 
 class BaseKPICalculatorModel(six.with_metaclass(abc.ABCMeta)):
-    @abc.abstractclassmethod
+    @classmethod
+    @abc.abstractmethod
     def from_json(self, model_data):
         pass
diff --git a/force_bdss/mco/base_mco_model.py b/force_bdss/mco/base_mco_model.py
index 9c7b159428c56b4340c231beae0df9378e9c3152..db861acd4f10b47c7f2f784f20ce7013df86dbb6 100644
--- a/force_bdss/mco/base_mco_model.py
+++ b/force_bdss/mco/base_mco_model.py
@@ -3,6 +3,7 @@ import six
 
 
 class BaseMCOModel(six.with_metaclass(abc.ABCMeta)):
-    @abc.abstractclassmethod
+    @classmethod
+    @abc.abstractmethod
     def from_json(self, model_data):
         pass