diff --git a/example/rp/index.html b/example/rp/index.html
index 16c540bcd1411dd88c8bb5d49d22b2c6a647fa6f..42391bbc9656f6808f3a87f9929c3736b4ac7a92 100644
--- a/example/rp/index.html
+++ b/example/rp/index.html
@@ -171,7 +171,7 @@ $(document).ready(function() {
   $(".specify button.assertion").click(function() {
     var requiredEmail = $.trim($('#requiredEmail').val());
     if (!requiredEmail.length) requiredEmail = undefined;
-    if (requiredEmail.indexOf('@') === -1) {
+    if (requiredEmail && requiredEmail.indexOf('@') === -1) {
       alert('Invalid Email in "Require a specific email" field. Adding @example.com');
       $('#requiredEmail').val(requiredEmail + '@example.com');
       $('#requiredEmail').focus();