Problem with admin-ajax.php adding '0' to the end of JSON response

I’m having a peculiar problem with admin-ajax.php where anything I send it, it will return a ‘0’ at the end of the response content. For exmample, I have in my code this:

function myAjaxCallback() {
    print 1;
}
add_action('wp_ajax_myAjax', 'myAjaxCallback');

The javascript side is like this:

jQuery.post(ajaxurl, {action:'myAjax'}, function(result) {
    console.log(result);
}

In my debug message I would expect just ‘1’, but I’m getting ’10’. It happens no matter what I print in the ajax callback function. I have no idea what’s doing this, so any help would be appreciated.

Should also note that this is in a plugin I’m working on, and it’s happening on both the post.php page and widgets.php page.