diff --git a/product/ERP5Type/Base.py b/product/ERP5Type/Base.py
index 6fe0036ef3a2f4ceae9b465a8a709060df7c829a..16325533be9b25e94e1255c8d4b63a27394f74bc 100644
--- a/product/ERP5Type/Base.py
+++ b/product/ERP5Type/Base.py
@@ -652,7 +652,8 @@ class Base( CopyContainer,
     # Test presence of attribute without acquisition
     # if present, get it in its context, thus we keep acquisition if
     # returned value is an object
-    if hasattr(aq_base(self), storage_id):
+    d = getattr(aq_base(self), storage_id, _MARKER)
+    if d is not _MARKER:
       value = getattr(self, storage_id, None)
     else:
       value = None