diff --git a/static/js/update-timeout-modal.js b/static/js/update-timeout-modal.js
index a1222780..3684937d 100644
--- a/static/js/update-timeout-modal.js
+++ b/static/js/update-timeout-modal.js
@@ -243,7 +243,7 @@ $(function () {
                 }
 
                 $("#oncalendar-preview" ).html(data);
-                var haveError = $("#invalid-arguments").length > 0;
+                var haveError = $("#invalid-oncalendar-arguments").length > 0;
                 $("#update-oncalendar-submit").prop("disabled", haveError);
             }
         });
diff --git a/templates/front/oncalendar_preview.html b/templates/front/oncalendar_preview.html
index 1b6820a4..8d8e976f 100644
--- a/templates/front/oncalendar_preview.html
+++ b/templates/front/oncalendar_preview.html
@@ -1,9 +1,9 @@
 {% load humanize tz %}
 
 {% if bad_schedule %}
-<p id="invalid-arguments">Invalid OnCalendar expression.</p>
+<p id="invalid-oncalendar-arguments">Invalid OnCalendar expression.</p>
 {% elif bad_tz %}
-<p id="invalid-arguments">Invalid timezone.</p>
+<p id="invalid-oncalendar-arguments">Invalid timezone.</p>
 {% else %}
 <table class="table">
     <tr><th id="oncalendar-preview-title" colspan="2">Expected Ping Dates</th></tr>