diff --git a/addons/payment_demo/views/payment_demo_templates.xml b/addons/payment_demo/views/payment_demo_templates.xml
index c90be710f7c..3d48cc8e37a 100644
--- a/addons/payment_demo/views/payment_demo_templates.xml
+++ b/addons/payment_demo/views/payment_demo_templates.xml
@@ -66,7 +66,7 @@
                  aria-labelledby="o_payment_demo_modal_label"
                  aria-hidden="true"
             >
-                <div class="modal-dialog">
+                <div class="modal-dialog modal-dialog-centered">
                     <div class="modal-content">
                         <div class="modal-header">
                             <h5 class="modal-title" id="o_payment_demo_modal_label">