diff --git a/apis_instance_nsvis/models.py b/apis_instance_nsvis/models.py
index 7584732..1ad1fc3 100644
--- a/apis_instance_nsvis/models.py
+++ b/apis_instance_nsvis/models.py
@@ -22,9 +22,12 @@ class MongoDbModel(models.Model):
     content_object = GenericForeignKey("content_type", "object_id")
 
 
-class MongoDbDataMixin:
+class MongoDbDataMixin(models.Model):
     mongodbdata = GenericRelation(MongoDbModel)
 
+    class Meta:
+        abstract = True
+
 
 class Person(E21_Person, AbstractEntity, VersionMixin, MongoDbDataMixin):
     biography = models.TextField(blank=True, verbose_name=_("Biography"))