diff --git a/static/main.js b/static/main.js
index 3f8c7ac..ee19a8a 100644
--- a/static/main.js
+++ b/static/main.js
@@ -15,10 +15,14 @@
                     event.preventDefault();
                     event.stopPropagation();
                 }
+                update_total_due();
                 form.classList.add('was-validated');
             }, false);
         });
     }, false);
+    window.addEventListener('popstate', function(event) {
+        update_total_due();
+    }, false);
 })();
 
 function update_total_due() {
@@ -39,6 +43,9 @@
         if ($('#conference_dinner').is(":checked")) {
             costs += parseInt($("#conference_dinner_price").text(), 10);
         }
+        if ($('#excursion').is(":checked")) {
+            costs += parseInt($("#excursion_price").text(), 10);
+        }
         const lunches = ["lunch_day_1", "lunch_day_2", "lunch_day_3"];
         lunches.forEach(function(lunch) {
             if ($("input[name='" + lunch + "']:checked").val() != "--") {