diff --git a/autoload/emmet/lang/html.vim b/autoload/emmet/lang/html.vim
index 328145f..37d43e5 100644
--- a/autoload/emmet/lang/html.vim
+++ b/autoload/emmet/lang/html.vim
@@ -427,6 +427,7 @@ function! emmet#lang#html#toString(settings, current, type, inline, filters, ite
         if attr == 'class' | let comment .= '.' . Val | endif
       endif
     endif
+    unlet Val
   endfor
   if len(comment) > 0
     let str = "<!-- " . comment . " -->\n" . str