diff --git a/addons/stock/wizard/stock_return_picking.py b/addons/stock/wizard/stock_return_picking.py
index bc6acfaa1cc..80cc5a4a368 100644
--- a/addons/stock/wizard/stock_return_picking.py
+++ b/addons/stock/wizard/stock_return_picking.py
@@ -100,8 +100,7 @@ class stock_return_picking(osv.osv_memory):
             valid_lines = 0
             return_history = self.get_return_history(cr, uid, record_id, context)
             for m  in pick.move_lines:
-                if return_history and return_history.get(m.id):
-                    if m.product_qty * m.product_uom.factor > return_history[m.id]:
+                 if (return_history.get(m.id) is not None) and (m.product_qty * m.product_uom.factor > return_history[m.id]):
                         valid_lines += 1
             if not valid_lines:
                 raise osv.except_osv(_('Warning!'), _("No products to return (only lines in Done state and not fully returned yet can be returned)!"))