Slidify no longer renders accent marks

Question

I usually insert accent marks in my slide decks using the utf-8 symbol (i.e. í, é, á, ó, ú, ñ). Today when I used slidify("index.Rmd") I received the following warning:

Blogification Successful :-)
Mensajes de aviso perdidos
1: In native_encode(text) :
   some characters may not work under the current locale

I am not aware of having made any changes other than updating to the newest version of RStudio. Any idea how I can get accent marks back? How can I change the current locale so that it renders utf-8 characters? I don't have this issue when I render a 'normal' .Rmd file (as an html file, for example).

EDIT: Here is some more information about my workflow.

I am using poirot and the blogify(".") command to render many slide decks at the same time in SublimeText3