diff --git a/addons/website_event/views/event_templates.xml b/addons/website_event/views/event_templates.xml
index f33f64c4f61..ad5b83b72f7 100644
--- a/addons/website_event/views/event_templates.xml
+++ b/addons/website_event/views/event_templates.xml
@@ -580,7 +580,7 @@
             </div>
         </div>
         <div class="col-lg-4 pt-3 pt-lg-0 pl-2 pl-lg-0">
-            <button type="submit" class="btn btn-primary btn-block a-submit" t-attf-id="#{event.id}">Register</button>
+            <button type="submit" class="btn btn-primary o_wait_lazy_js btn-block a-submit" t-attf-id="#{event.id}">Register</button>
         </div>
     </div>
     <div t-if="description" class="row mx-0">
diff --git a/addons/website_event_sale/views/event_templates.xml b/addons/website_event_sale/views/event_templates.xml
index 12a42ad99ed..117a1f02246 100644
--- a/addons/website_event_sale/views/event_templates.xml
+++ b/addons/website_event_sale/views/event_templates.xml
@@ -70,7 +70,7 @@
                 </div>
                 <div class="row no-gutters">
                     <div class="col-md-4 offset-md-8 py-2 pl-md-0 pr-md-2">
-                        <button type="submit" class="btn btn-primary btn-block a-submit" t-att-disabled="not tickets_available or None" t-attf-id="#{event.id}">Register</button>
+                        <button type="submit" class="btn btn-primary o_wait_lazy_js btn-block a-submit" t-att-disabled="not tickets_available or None" t-attf-id="#{event.id}">Register</button>
                     </div>
                 </div>
             </div>