diff --git a/addons/sale/models/sale.py b/addons/sale/models/sale.py
index fa2dd448c08..680f2e6cde6 100644
--- a/addons/sale/models/sale.py
+++ b/addons/sale/models/sale.py
@@ -442,6 +442,10 @@ class SaleOrder(models.Model):
     def action_done(self):
         self.write({'state': 'done'})
 
+    @api.multi
+    def action_unlock(self):
+        self.write({'state': 'sale'})
+
     @api.model
     def _prepare_procurement_group(self):
         return {'name': self.name}
diff --git a/addons/sale/views/sale_views.xml b/addons/sale/views/sale_views.xml
index 30ebc39e7ed..e8f6a34b9be 100644
--- a/addons/sale/views/sale_views.xml
+++ b/addons/sale/views/sale_views.xml
@@ -165,6 +165,7 @@
                     <button name="action_draft" states="cancel" type="object" string="Set to Quotation"/>
                     <button name="action_done" type="object" string="Lock" states="sale"
                         help="If the sale is locked, you can not modify it anymore. However, you will still be able to invoice or deliver."/>
+                    <button name="action_unlock" type="object" string="Unlock" states="done" groups="sales_team.group_sale_manager"/>
                     <field name="state" widget="statusbar" statusbar_visible="draft,sent,sale"/>
                 </header>
                 <sheet>