diff --git a/product/ERP5/Document/Event.py b/product/ERP5/Document/Event.py
index ada2e3c78d0e9246f780ff3064809fd48ae196b3..bab1a6791443e7635c12f8ed00a5fafc718576b0 100644
--- a/product/ERP5/Document/Event.py
+++ b/product/ERP5/Document/Event.py
@@ -84,7 +84,8 @@ class AcknowledgeableMixin:
                           user_name=user_name)
       if len(self.portal_catalog(portal_type='Acknowledgement',
                 default_causality_uid=self.getUid(),
-                default_destination_uid=person_value.getUid())) > 0:
+                default_destination_uid=person_value.getUid(),
+                limit=1)) > 0:
         result = True
     return result