diff --git a/product/ERP5/Document/PaySheetTransaction.py b/product/ERP5/Document/PaySheetTransaction.py
index 846edcc127f132e8fc4f7c08bd44fc6e5eac3c12..587a01a7103414b219dbd3992f71108f80963467 100644
--- a/product/ERP5/Document/PaySheetTransaction.py
+++ b/product/ERP5/Document/PaySheetTransaction.py
@@ -85,9 +85,9 @@ class PaySheetTransaction(Invoice):
     # if not find in the paysheet, look on dependence tree
     sub_object_list = self.getInheritedObjectValueList(portal_type_list)
     object_ratio_list = sub_object_list
-    for ob in object_ratio_list:
-      if ob.getReference() == ratio_reference:
-        return ob.getQuantity()
+    for document in object_ratio_list:
+      if document.getReference() == ratio_reference:
+        return document.getQuantity()
 
     return None