diff --git a/addons/purchase/purchase.py b/addons/purchase/purchase.py
index 344da2e70a6..a9d8e773b19 100644
--- a/addons/purchase/purchase.py
+++ b/addons/purchase/purchase.py
@@ -134,10 +134,7 @@ class purchase_order(osv.osv):
     def _invoiced(self, cursor, user, ids, name, arg, context=None):
         res = {}
         for purchase in self.browse(cursor, user, ids, context=context):
-            invoiced = False
-            if purchase.invoiced_rate == 100.00:
-                invoiced = True
-            res[purchase.id] = invoiced
+            res[purchase.id] = all(line.invoiced for line in purchase.order_line)
         return res
     
     def _get_journal(self, cr, uid, context=None):
@@ -544,7 +541,7 @@ class purchase_order(osv.osv):
                 inv_line_id = inv_line_obj.create(cr, uid, inv_line_data, context=context)
                 inv_lines.append(inv_line_id)
 
-                po_line.write({'invoiced': True, 'invoice_lines': [(4, inv_line_id)]}, context=context)
+                po_line.write({'invoice_lines': [(4, inv_line_id)]}, context=context)
 
             # get invoice data and create invoice
             inv_data = {
@@ -1290,9 +1287,15 @@ class account_invoice(osv.Model):
             user_id = uid
         po_ids = purchase_order_obj.search(cr, user_id, [('invoice_ids', 'in', ids)], context=context)
         wf_service = netsvc.LocalService("workflow")
-        for po_id in po_ids:
+        for order in purchase_order_obj.browse(cr, uid, po_ids, context=context):
             # Signal purchase order workflow that an invoice has been validated.
-            wf_service.trg_write(uid, 'purchase.order', po_id, cr)
+            invoiced = []
+            for po_line in order.order_line:
+                if any(line.invoice_id.state not in ['draft', 'cancel'] for line in po_line.invoice_lines):
+                    invoiced.append(po_line.id)
+            if invoiced:
+                self.pool['purchase.order.line'].write(cr, uid, invoiced, {'invoiced': True})
+            wf_service.trg_write(uid, 'purchase.order', order.id, cr)
         return res
 
 # vim:expandtab:smartindent:tabstop=4:softtabstop=4:shiftwidth=4:
diff --git a/addons/purchase/stock.py b/addons/purchase/stock.py
index e4a3252eef2..d0055d80c7f 100644
--- a/addons/purchase/stock.py
+++ b/addons/purchase/stock.py
@@ -111,7 +111,6 @@ class stock_picking(osv.osv):
             invoice_line_obj = self.pool.get('account.invoice.line')
             purchase_line_obj = self.pool.get('purchase.order.line') 
             purchase_line_obj.write(cursor, user, [move_line.purchase_line_id.id], {
-                'invoiced': True,
                 'invoice_lines': [(4, invoice_line_id)],
             })
         return super(stock_picking, self)._invoice_line_hook(cursor, user, move_line, invoice_line_id)