diff --git a/addons/stock/views/stock_picking_views.xml b/addons/stock/views/stock_picking_views.xml
index 243856fe84a..18b9def43f2 100644
--- a/addons/stock/views/stock_picking_views.xml
+++ b/addons/stock/views/stock_picking_views.xml
@@ -209,7 +209,7 @@
                     <button name="action_confirm" attrs="{'invisible': [('show_mark_as_todo', '=', False)]}" string="Mark as Todo" type="object" class="oe_highlight" groups="base.group_user"/>
                     <button name="action_assign" attrs="{'invisible': [('show_check_availability', '=', False)]}" string="Check Availability" type="object" class="oe_highlight" groups="base.group_user"/>
                     <button name="button_validate" attrs="{'invisible': ['|', ('state', 'in', ('waiting','confirmed')), ('show_validate', '=', False)]}" string="Validate" type="object" class="oe_highlight" groups="stock.group_stock_user"/>
-                    <button name="button_validate" attrs="{'invisible': ['|', ('state', 'not in', ('waiting', 'confirmed')), ('show_validate', '=', False)]}" string="Validate" type="object" groups="stock.group_stock_user"/>
+                    <button name="button_validate" attrs="{'invisible': ['|', ('state', 'not in', ('waiting', 'confirmed')), ('show_validate', '=', False)]}" string="Validate" type="object" groups="stock.group_stock_user" class="o_btn_validate"/>
                     <button name="do_print_picking" string="Print" groups="stock.group_stock_user" type="object" attrs="{'invisible': ['|', ('state', 'not in', ('assigned', 'partially_available')), ('is_locked', '=', False)]}"/>
                     <button name="%(action_report_delivery)d" string="Print" attrs="{'invisible': ['|', ('state', '!=', 'done'), ('is_locked', '=', False)]}" type="action" groups="base.group_user"/>
                     <button name="%(act_stock_return_picking)d" string="Return" attrs="{'invisible': ['|', ('state', '!=', 'done'), ('is_locked', '=', False)]}" type="action" groups="base.group_user"/>