diff --git a/lib/6to5/file.js b/lib/6to5/file.js
index 2fcb5012ec..b1fc6733c5 100644
--- a/lib/6to5/file.js
+++ b/lib/6to5/file.js
@@ -95,20 +95,22 @@ File.prototype.generate = function () {
   var ast  = this.ast;
 
   var result = util.generate(ast, opts);
+  var code   = result.code;
 
   if (this.shebang) {
     // add back shebang
-    result.code = this.shebang + result.code;
+    code = this.shebang + code;
   }
 
   if (opts.sourceMap === "inline") {
-    result.code += "\n" + util.sourceMapToComment(result.map);
+    code += "\n" + util.sourceMapToComment(map);
   }
 
-  result.map = result.map || null;
-  result.ast = ast;
-
-  return result;
+  return {
+    code: code,
+    map:  result.map || null,
+    ast:  ast
+  };
 };
 
 File.prototype.generateUid = function (name) {