diff -r 40135dd78b5b -r c528e2eb7172 src/pyams_default_theme/shared/view/portlet/__init__.py
--- a/src/pyams_default_theme/shared/view/portlet/__init__.py	Wed Dec 12 10:17:05 2018 +0100
+++ b/src/pyams_default_theme/shared/view/portlet/__init__.py	Wed Dec 12 11:15:25 2018 +0100
@@ -14,7 +14,7 @@
 
 from persistent import Persistent
 from zope.container.contained import Contained
-from zope.interface import Interface, implementer
+from zope.interface import Interface
 from zope.schema.fieldproperty import FieldProperty
 
 from pyams_content.shared.view.portlet.interfaces import IViewItemsPortletSettings
@@ -30,7 +30,6 @@
 
 
 @factory_config(provided=IViewItemsPortletVerticalRendererSettings)
-@implementer(IViewItemsPortletVerticalRendererSettings)
 class ViewItemsPortletVerticalRendererSettings(Persistent, Contained):
     """View items portlet renderer settings"""