diff --git a/product/ERP5Form/ListBox.py b/product/ERP5Form/ListBox.py
index 4327082ee84784c78def1a2e1d90be59d2a62783..35c26d165ef6a3aa417a805e8b1547b896ac109d 100755
--- a/product/ERP5Form/ListBox.py
+++ b/product/ERP5Form/ListBox.py
@@ -680,7 +680,7 @@ class ListBoxWidget(Widget.Widget):
         # selection is the same
         sorted_object_uid_list = copy(object_uid_list)
         sorted_object_uid_list.sort()
-        md5_string = escape(md5.new(str(sorted_object_uid_list)).digest())
+        md5_string = escape(md5.new(str(sorted_object_uid_list)).hexdigest())
         #md5_string = md5.new(str(object_uid_list)).digest()