diff --git a/account_invoice_split_sale/__init__.py b/account_invoice_split_sale/__init__.py
index 02baef47b981..a1e27b0338e6 100644
--- a/account_invoice_split_sale/__init__.py
+++ b/account_invoice_split_sale/__init__.py
@@ -1,2 +1,3 @@
 # -*- coding: utf-8 -*-
 from . import wizard
+from . import models
diff --git a/account_invoice_split_sale/models/__init__.py b/account_invoice_split_sale/models/__init__.py
new file mode 100644
index 000000000000..6064afee1782
--- /dev/null
+++ b/account_invoice_split_sale/models/__init__.py
@@ -0,0 +1,3 @@
+# -*- coding: utf-8 -*-
+
+from . import sale_order
diff --git a/account_invoice_split_sale/models/sale_order.py b/account_invoice_split_sale/models/sale_order.py
new file mode 100644
index 000000000000..0193e9f448d3
--- /dev/null
+++ b/account_invoice_split_sale/models/sale_order.py
@@ -0,0 +1,46 @@
+# -*- coding: utf-8 -*-
+#
+##############################################################################
+#
+#    Authors: Adrien Peiffer
+#    Copyright (c) 2015 Acsone SA/NV (http://www.acsone.eu)
+#
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU Affero General Public License as
+#    published by the Free Software Foundation, either version 3 of the
+#    License, or (at your option) any later version.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU Affero General Public License for more details.
+#
+#    You should have received a copy of the GNU Affero General Public License
+#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+##############################################################################
+
+from openerp import models, api
+
+
+class SaleOrder(models.Model):
+    _inherit = 'sale.order'
+
+    @api.cr_context
+    def _auto_init(self, cr, context=None):
+        """ hack: pre-create and initialize the picking_policy column so that
+        the constraint setting will not fail, this is a hack, made necessary
+        because Odoo tries to set the not-null constraint before
+        applying default values """
+        self._field_create(cr, context=context)
+        column_data = self._select_column_data(cr)
+        if 'picking_policy' not in column_data:
+            default_picking_policy = 'picking_policy'
+            if default_picking_policy:
+                cr.execute("""ALTER TABLE "{table}" ADD COLUMN
+                    "picking_policy" character varying""".format(table=
+                                                                 self._table))
+                cr.execute("""UPDATE "{table}" SET
+                    picking_policy='picking_policy'""".
+                           format(table=self._table))
+        return super(SaleOrder, self)._auto_init(cr, context=context)