diff --git a/addons/purchase/purchase.py b/addons/purchase/purchase.py
index e3b0fa5bfd9..8059e2d7788 100644
--- a/addons/purchase/purchase.py
+++ b/addons/purchase/purchase.py
@@ -149,19 +149,6 @@ class purchase_order(osv.osv):
                                                 limit=1)
         return res and res[0] or False  
 
-    def _has_non_stockable_item(self, cr, uid, ids, *args):
-        res = dict.fromkeys(ids, False)
-        for order in self.browse(cr, uid, ids):
-            for order_line in order.order_line:
-                if (
-                    not order_line.product_id
-                    or
-                    order_line.product_id
-                    and order_line.product_id.type not in ('product', 'consu')
-                ):
-                    res[order.id] = True
-        return res
-
     STATE_SELECTION = [
         ('draft', 'Draft PO'),
         ('sent', 'RFQ Sent'),
@@ -237,7 +224,6 @@ class purchase_order(osv.osv):
         'create_uid':  fields.many2one('res.users', 'Responsible'),
         'company_id': fields.many2one('res.company','Company',required=True,select=1, states={'confirmed':[('readonly',True)], 'approved':[('readonly',True)]}),
         'journal_id': fields.many2one('account.journal', 'Journal'),
-        'has_non_stockable_item': fields.function(_has_non_stockable_item, method=True, type='boolean', string='Contains a non-stockable item'),
     }
     _defaults = {
         'date_order': fields.date.context_today,
@@ -485,10 +471,10 @@ class purchase_order(osv.osv):
         for po in self.browse(cr, uid, ids, context=context):
             if not po.order_line:
                 raise osv.except_osv(_('Error!'),_('You cannot confirm a purchase order without any purchase order line.'))
-            if po.invoice_method == 'picking' and po.has_non_stockable_item is True:
+            if po.invoice_method == 'picking' and not any([l.product_id and l.product_id.type in ('product', 'consu') for l in po.order_line]):
                 raise osv.except_osv(
                     _('Error!'),
-                    _("You cannot confirm a purchase order with Invoice Control Method 'Based on incoming shipments' that contains non-stockable items."))
+                    _("You cannot confirm a purchase order with Invoice Control Method 'Based on incoming shipments' that doesn't contain any stockable item."))
             for line in po.order_line:
                 if line.state=='draft':
                     todo.append(line.id)