R: table of contents unused argument in tufte_handout in rmarkdown

Question

I am trying to add table of contentsinto tufte_handout template in rmarkdown package as it is suggest here at the bottom of a page but when I creat yaml like this:

---
title: "Tufte Handout"
author: "John Smith"
date: "August 13th, 2014"
output: 
  rmarkdown::tufte_handout:
    toc: true
---

I recieve an error like this:

Error in (function (fig_width = 4, fig_height = 2.5, fig_crop = TRUE,  : 
  unused argument (toc = TRUE)
Calls: <Anonymous> -> create_output_format -> do.call -> <Anonymous>
Execution halted

Anyone knows how to handle this issue?