diff --git a/lib/6to5/util.js b/lib/6to5/util.js
index 4ecb4baa5b..423180c532 100644
--- a/lib/6to5/util.js
+++ b/lib/6to5/util.js
@@ -203,13 +203,11 @@ exports.parse = function (opts, code, callback) {
 
     estraverse.attachComments(ast, comments, tokens);
 
-    ast = {
-      type:    "File",
-      program: ast,
+    ast = t.file(ast, comments, tokens);
 
-      comments: comments,
-      tokens:   tokens,
-    };
+    traverse(ast, function (node, parent) {
+      node._parent = parent;
+    });
 
     if (callback) {
       return callback(ast);