diff --git a/app/static/app.js b/app/static/app.js
index dfa8537..77b2a91 100644
--- a/app/static/app.js
+++ b/app/static/app.js
@@ -283,7 +283,7 @@ function submitPdf(eve) {
   submitForm(formdata);
 }
 async function submitForm(formData) {
-  var updateEventSource = None;
+  var updateEventSource = null;
   try {
     updateEventSource = new EventSource("/get_censor_status/" + doc.fID);
 
@@ -305,7 +305,7 @@ async function submitForm(formData) {
       method: "POST",
       body: formData,
     });
-    if (updateEventSource !== None) {
+    if (updateEventSource !== null) {
       updateEventSource.close();
     }
     modal.style.display = "none";