Sticky posts don't show up first in custom loop

Question

I'm using the following query in my frontpage template:

        <?php $paged = get_query_var( 'paged' ) ? get_query_var( 'paged' ) : 1;
        $args=array(
          'paged'           => $paged,
          'category_name'   =>'home,tumblr'
        );
        query_posts($args);

But for some reason, posts that are made sticky in either of these categories do not show up as the first posts in the output of the loop. It seems option is ignored somehow? How can I make sticky posts show up first?