diff --git a/account_constraints/account_constraints.py b/account_constraints/account_constraints.py
index 63a0912c6..b8a4c267c 100644
--- a/account_constraints/account_constraints.py
+++ b/account_constraints/account_constraints.py
@@ -47,8 +47,8 @@ class AccountMoveLine(orm.Model):
     def _check_invoice_related_move(self, cr, uid, ids, context=None):
         for line in self.browse(cr, uid, ids, context=context):
             if line.invoice:
-                err_msg = _('Invoice name (id): %s (%s)') %
-                            (line.invoice.name, str(line.invoice.id))
+                err_msg = (_('Invoice name (id): %s (%s)') %
+                            (line.invoice.name, str(line.invoice.id)))
                 raise osv.except_osv(
                     _('Error'),
                     _('You cannot do this on an entry generated by an invoice. You must '
@@ -58,8 +58,8 @@ class AccountMoveLine(orm.Model):
     def _check_statement_related_move(self, cr, uid, ids, context=None):
         for line in self.browse(cr, uid, ids, context=context):
             if line.statement_id:
-                err_msg = _('Bank statement name (id): %s (%s)') %
-                            (line.statement_id.name, str(line.statement_id.id))
+                err_msg = (_('Bank statement name (id): %s (%s)') %
+                            (line.statement_id.name, str(line.statement_id.id)))
                 raise osv.except_osv(
                     _('Error'),
                     _('You cannot do this on an entry generated by a bank statement. '