diff --git a/marshmallow_jsonschema/base.py b/marshmallow_jsonschema/base.py
index c7ffbbc..f31b4f7 100644
--- a/marshmallow_jsonschema/base.py
+++ b/marshmallow_jsonschema/base.py
@@ -151,7 +151,7 @@ def __init__(self, *args, **kwargs) -> None:
 
     def get_properties(self, obj) -> typing.Dict[str, typing.Dict[str, typing.Any]]:
         """Fill out properties field."""
-        properties = self.dict_class()
+        properties = obj.dict_class()
 
         if self.props_ordered:
             fields_items_sequence = obj.fields.items()