diff --git a/addons/sale/data/ir_sequence_data.xml b/addons/sale/data/ir_sequence_data.xml
index 8e4559a0cdf..42859382008 100644
--- a/addons/sale/data/ir_sequence_data.xml
+++ b/addons/sale/data/ir_sequence_data.xml
@@ -6,7 +6,7 @@
         <record id="seq_sale_order" model="ir.sequence">
             <field name="name">Sales Order</field>
             <field name="code">sale.order</field>
-            <field name="prefix">SO</field>
+            <field name="prefix">S</field>
             <field name="padding">3</field>
             <field name="company_id" eval="False"/>
         </record>
diff --git a/addons/website_sale/static/tests/tours/website_sale_shop_mail.js b/addons/website_sale/static/tests/tours/website_sale_shop_mail.js
index d5a998500ed..eb82dcd9840 100644
--- a/addons/website_sale/static/tests/tours/website_sale_shop_mail.js
+++ b/addons/website_sale/static/tests/tours/website_sale_shop_mail.js
@@ -94,7 +94,7 @@ tour.register('shop_mail', {
     },
     {
         content: "click on the first email",
-        trigger: '.o_data_cell:contains("(Ref SO")',
+        trigger: '.o_data_cell:contains("(Ref S")',
     },
     {
         content: "check it's the correct email, and the URL is correct too",