diff --git a/lib/6to5/transformation/transformers/classes.js b/lib/6to5/transformation/transformers/classes.js
index a989c96ab7..1e0aa0dc2a 100644
--- a/lib/6to5/transformation/transformers/classes.js
+++ b/lib/6to5/transformation/transformers/classes.js
@@ -4,7 +4,7 @@ var t        = require("../../types");
 var _        = require("lodash");
 
 exports.ClassDeclaration = function (node, parent, file, scope) {
-  return t.variableDeclaration("var", [
+  return t.variableDeclaration("let", [
     t.variableDeclarator(node.id, new Class(node, file, scope).run())
   ]);
 };