diff --git a/addons/procurement/procurement.py b/addons/procurement/procurement.py
index 3257f0a5694..83ce42034df 100644
--- a/addons/procurement/procurement.py
+++ b/addons/procurement/procurement.py
@@ -289,9 +289,15 @@ class procurement_order(osv.osv):
                 return False
             partner = procurement.product_id.seller_id #Taken Main Supplier of Product of Procurement.
 
+            if not partner:
+                cr.execute('update procurement_order set message=%s where id=%s',
+                           (_('No default supplier defined for this product'), procurement.id))
+                return False
+
             if user.company_id and user.company_id.partner_id:
                 if partner.id == user.company_id.partner_id.id:
                     return False
+
             address_id = partner_obj.address_get(cr, uid, [partner.id], ['delivery'])['delivery']
             if not address_id:
                 cr.execute('update procurement_order set message=%s where id=%s',
diff --git a/addons/product/product.py b/addons/product/product.py
index 6bee68c2ba6..f82e5791fd7 100644
--- a/addons/product/product.py
+++ b/addons/product/product.py
@@ -250,7 +250,9 @@ class product_template(osv.osv):
                 result[product.id] = {field:False}
             result[product.id]['seller_delay'] = 1
             if product.seller_ids:
-                partner_list = sorted([(partner_id.sequence, partner_id) for partner_id in  product.seller_ids if partner_id and partner_id.sequence])
+                partner_list = sorted([(partner_id.sequence, partner_id)
+                                       for partner_id in  product.seller_ids
+                                       if partner_id and isinstance(partner_id.sequence, (int, long))])
                 main_supplier = partner_list and partner_list[0] and partner_list[0][1] or False
                 result[product.id]['seller_delay'] =  main_supplier and main_supplier.delay or 1
                 result[product.id]['seller_qty'] =  main_supplier and main_supplier.qty or 0.0