diff --git a/app/assets/javascripts/discourse/lib/markdown.js b/app/assets/javascripts/discourse/lib/markdown.js
index 7d408619517..e3a629314ca 100644
--- a/app/assets/javascripts/discourse/lib/markdown.js
+++ b/app/assets/javascripts/discourse/lib/markdown.js
@@ -160,7 +160,7 @@ Discourse.Markdown = {
     @return {String} text The sanitized text
   **/
   sanitize: function(text) {
-    if (!window.html_sanitize) return "";
+    if (!window.html_sanitize || !text) return "";
     text = text.replace(/<([^A-Za-z\/]|$)/g, "&lt;$1");
     return window.html_sanitize(text, Discourse.Markdown.urlAllowed, Discourse.Markdown.nameIdClassAllowed);
   },