luciendub on "strtotime returns strange characters"

I want to show date of events created via custom post type and ACF in WordPress. I try to figure out why this:

<?php setlocale(LC_TIME, 'fr_FR'); echo strftime('%d %h %Y', strtotime(get_field('date_de_levenement'))); ?>

returns strange characters like this:

04 ao�t 2014

(Here the 04 ao�t 2014 should be 04 août 2014)