Mbconvert error in RSS feed

I enabled markdown extras in my config:
c::set(‘markdown.extra’, true);¬

And now I get the following error when loading my RSS feed.
Call to undefined function mb_convert_encoding()



What do I need to add to my feed template to fix this error?

Is the mb_string extension installed, see requirements?

Thanks, I had to enabled it in a php.ini file, and wasn’t doing it in the right place.