diff --git a/addons/purchase/purchase.py b/addons/purchase/purchase.py
index 355267229f6..e57e2833c8d 100644
--- a/addons/purchase/purchase.py
+++ b/addons/purchase/purchase.py
@@ -452,6 +452,8 @@ class purchase_order_line(osv.osv):
             partner_id, date_order=False, fiscal_position=False):
         if not pricelist:
             raise osv.except_osv(_('No Pricelist !'), _('You have to select a pricelist in the purchase form !\nPlease set one before choosing a product.'))
+        if not  partner_id:
+            raise osv.except_osv(_('No Partner!'), _('You have to select a partner in the purchase form !\nPlease set one partner before choosing a product.'))
         if not product:
             return {'value': {'price_unit': 0.0, 'name':'','notes':'', 'product_uom' : False}, 'domain':{'product_uom':[]}}
         prod= self.pool.get('product.product').browse(cr, uid,product)
diff --git a/addons/sale/sale.py b/addons/sale/sale.py
index 11908284f05..c58c81efa57 100644
--- a/addons/sale/sale.py
+++ b/addons/sale/sale.py
@@ -851,8 +851,8 @@ class sale_order_line(osv.osv):
     def product_id_change(self, cr, uid, ids, pricelist, product, qty=0,
             uom=False, qty_uos=0, uos=False, name='', partner_id=False,
             lang=False, update_tax=True, date_order=False, packaging=False, fiscal_position=False):
-        if not  pricelist:
-            raise osv.except_osv(_('No Pricelist !'), _('You have to select a pricelist in the sale form !\nPlease set one partner before choosing a product.'))
+        if not  partner_id:
+            raise osv.except_osv(_('No Partner !'), _('You have to select a partner in the sale form !\nPlease set one partner before choosing a product.'))
         warning={}
         product_uom_obj = self.pool.get('product.uom')
         partner_obj = self.pool.get('res.partner')