diff --git a/product/ERP5Type/Base.py b/product/ERP5Type/Base.py
index f133f11347e33f98af40aa1e3971ad5a30ad9380..860e14ead7acbc83df32dbda2da44061e4427c79 100644
--- a/product/ERP5Type/Base.py
+++ b/product/ERP5Type/Base.py
@@ -117,6 +117,8 @@ def resetRegisteredWorkflowMethod(portal_type=None):
   for method in workflow_method_registry:
     method.reset(portal_type=portal_type)
 
+  del workflow_method_registry[:]
+
 class WorkflowMethod(Method):
 
   def __init__(self, method, id=None, reindex=1):