diff --git a/app/views/member/blog/update_theme.html b/app/views/member/blog/update_theme.html
index d39871d..e659451 100644
--- a/app/views/member/blog/update_theme.html
+++ b/app/views/member/blog/update_theme.html
@@ -265,6 +265,7 @@ var theme = {
 			lang = "css";
 		}
 		editor.setValue(content);
+		editor.getSession().setUndoManager(new ace.UndoManager());
 		editor.session.setMode("ace/mode/" + lang);
 		editor.gotoLine(1);
 		setTimeout(function() {