diff --git a/homepage/knowledge/cat.html b/homepage/knowledge/cat.html
index be05f9d..f2b23f7 100644
--- a/homepage/knowledge/cat.html
+++ b/homepage/knowledge/cat.html
@@ -48,7 +48,7 @@ window.load_highlighting = function(language){
 			var elements = document.getElementsByClassName("language-" + language);
 			for(var i = 0; i < elements.length; ++i)
 				try{
-					hljs.highlightElement(element);
+					hljs.highlightElement(elements[i]);
 				}catch(err){
 					console.log(err.message);
 				}