diff --git a/public/react/public/js/editormd/editormd.min.js b/public/react/public/js/editormd/editormd.min.js
index e911b76ad..79c072919 100755
--- a/public/react/public/js/editormd/editormd.min.js
+++ b/public/react/public/js/editormd/editormd.min.js
@@ -3602,7 +3602,7 @@
             return text;
         };
         markedRenderer.em = function (text) {
-            if (text && text.substring('$$') != -1) {
+            if (text && text.indexOf('$$') != -1) {
                 return text;
             } else {
                 return '<em>' + text + '</em>';