diff --git a/marshmallow_jsonschema/base.py b/marshmallow_jsonschema/base.py
index 1096363..2db5a3d 100644
--- a/marshmallow_jsonschema/base.py
+++ b/marshmallow_jsonschema/base.py
@@ -326,7 +326,7 @@ def _from_nested_schema(self, obj, field):
             self._nested_schema_classes.update(wrapped_nested._nested_schema_classes)
 
         # and the schema is just a reference to the def
-        schema = {"type": "object", "$ref": "#/definitions/{}".format(name)}
+        schema = self._schema_base(name)
 
         # NOTE: doubled up to maintain backwards compatibility
         metadata = field.metadata.get("metadata", {})
@@ -348,6 +348,9 @@ def _from_nested_schema(self, obj, field):
 
         return schema
 
+    def _schema_base(self, name):
+        return {"type": "object", "$ref": "#/definitions/{}".format(name)}
+
     def dump(self, obj, **kwargs):
         """Take obj for later use: using class name to namespace definition."""
         self.obj = obj