diff --git a/public/src/client/topic/images.js b/public/src/client/topic/images.js
index a04b22a9e9..7506790fff 100644
--- a/public/src/client/topic/images.js
+++ b/public/src/client/topic/images.js
@@ -24,7 +24,7 @@ define('forum/topic/images', [], function () {
 
 			if (!$this.parent().is('a')) {
 				$this.wrap('<a href="' + src + '" ' +
-					(!srcExt && altExt ? ' download="' + altFilename + '" ' : '') +
+					(!srcExt && altExt ? ' download="' + utils.escapeHTML(altFilename) + '" ' : '') +
 					' target="_blank" rel="noopener">');
 			}
 		});