diff --git a/auquotidien/modules/payments.py b/auquotidien/modules/payments.py
index 24d82bd..48fd2ec 100644
--- a/auquotidien/modules/payments.py
+++ b/auquotidien/modules/payments.py
@@ -31,7 +31,7 @@ from wcs.qommon.misc import simplify
 
 from wcs.formdef import FormDef
 from wcs.formdata import Evolution
-from wcs.workflows import WorkflowStatusItem, register_item_class, template_on_formdata
+from wcs.workflows import EvolutionPart, WorkflowStatusItem, register_item_class, template_on_formdata
 
 
 def is_payment_supported():
@@ -162,7 +162,7 @@ INVOICE_EVO_VIEW = {
 }
 
 
-class InvoiceEvolutionPart:
+class InvoiceEvolutionPart(EvolutionPart):
     action = None
     id = None
     subject = None