diff --git a/lib/6to5/transformation/modules/system.js b/lib/6to5/transformation/modules/system.js
index f921c05e14..e0bd3ef35f 100644
--- a/lib/6to5/transformation/modules/system.js
+++ b/lib/6to5/transformation/modules/system.js
@@ -1,11 +1,10 @@
 module.exports = SystemFormatter;
 
-var DefaultFormatter = require("./_default");
-var AMDFormatter     = require("./amd");
-var traverse         = require("../../traverse");
-var util             = require("../../util");
-var t                = require("../../types");
-var _                = require("lodash");
+var AMDFormatter = require("./amd");
+var traverse     = require("../../traverse");
+var util         = require("../../util");
+var t            = require("../../types");
+var _            = require("lodash");
 
 function SystemFormatter(file) {
   this.exportIdentifier  = file.generateUidIdentifier("export");