diff --git a/app/assets/javascripts/pretty-text/engines/discourse-markdown/upload-protocol.js b/app/assets/javascripts/pretty-text/engines/discourse-markdown/upload-protocol.js
index 2a4310ac0e2..f3a675da1f6 100644
--- a/app/assets/javascripts/pretty-text/engines/discourse-markdown/upload-protocol.js
+++ b/app/assets/javascripts/pretty-text/engines/discourse-markdown/upload-protocol.js
@@ -6,8 +6,9 @@ const HTML_TYPES = ["html_block", "html_inline"];
 function addImage(uploads, token) {
   if (token.attrs) {
     for (let i = 0; i < token.attrs.length; i++) {
-      if (token.attrs[i][1].indexOf("upload://") === 0) {
-        uploads.push({ token, srcIndex: i, origSrc: token.attrs[i][1] });
+      const value = token.attrs[i][1];
+      if (value?.startsWith("upload://")) {
+        uploads.push({ token, srcIndex: i, origSrc: value });
         break;
       }
     }