Facebook Page Plugin width doesn't apply

I'm trying to implement the Facebook Page Plugin. I set the width to 500, but it always stays at 280px.

<div id="facebook-feed" style="text-align: center">
            <div class="fb-page zdepth-1" data-width="400" data-href="http://ift.tt/MKrQcH" data-hide-cover="false" data-show-facepile="true" data-show-posts="true"></div>
</div>

What am I doing wrong?