diff --git a/reclass/storage/yaml_fs/__init__.py b/reclass/storage/yaml_fs/__init__.py
index d06b406..35e4f05 100644
--- a/reclass/storage/yaml_fs/__init__.py
+++ b/reclass/storage/yaml_fs/__init__.py
@@ -98,7 +98,7 @@
         entity = YamlData.from_file(path).get_entity(name)
         return entity
 
-    def get_class(self, name, environment=None):
+    def get_class(self, name, environment):
         vvv('GET CLASS {0}'.format(name))
         try:
             path = os.path.join(self.classes_uri, self._classes[name])