diff --git a/product/ERP5Form/SelectionTool.py b/product/ERP5Form/SelectionTool.py
index 9530f9af84e2e6c9a722d4a1086170e8ace3b57f..f31fd88153ba744ce617a7d3977b0c565375e2a4 100755
--- a/product/ERP5Form/SelectionTool.py
+++ b/product/ERP5Form/SelectionTool.py
@@ -739,7 +739,7 @@ class SelectionTool( UniqueObject, SimpleItem ):
       # XXX Remove DateTime, This is really bad, only use for zope 2.6
       # XXX This has to be removed as quickly as possible
       for k,v in kw.items():
-        if instance(v,DateTime):
+        if isinstance(v,DateTime):
           del kw[k]
       # XXX End of the part to remove
       pickle_string = pickle.dumps(kw)