Display "Yesterday" instead of "1 day ago"

How should I modify this relative date script to display "Yesterday" instead of "1 day ago"?

    if(!function_exists('how_long_ago')){
        function how_long_ago($timestamp){
            $difference = time() - $timestamp;

            if($difference >= 60*60*24*365){        // if more than a year ago
                $int = intval($difference / (60*60*24*365));
                $s = ($int > 1) ? 's' : '';
                $r = $int . ' year' . $s . ' ago';
            } elseif($difference >= 60*60*24*7*5){  // if more than five weeks ago
                $int = intval($difference / (60*60*24*30));
                $s = ($int > 1) ? 's' : '';
                $r = $int . ' month' . $s . ' ago';
            } elseif($difference >= 60*60*24*7){        // if more than a week ago
                $int = intval($difference / (60*60*24*7));
                $s = ($int > 1) ? 's' : '';
                $r = $int . ' week' . $s . ' ago';
            } elseif($difference >= 60*60*24){      // if more than a day ago
                $int = intval($difference / (60*60*24));
                $s = ($int > 1) ? 's' : '';
                $r = $int . ' day' . $s . ' ago';
            } elseif($difference >= 60*60){         // if more than an hour ago
                $int = intval($difference / (60*60));
                $s = ($int > 1) ? 's' : '';
                $r = $int . ' hour' . $s . ' ago';
            } elseif($difference >= 60){            // if more than a minute ago
                $int = intval($difference / (60));
                $s = ($int > 1) ? 's' : '';
                $r = $int . ' minute' . $s . ' ago';
            } else {                                // if less than a minute ago
                $r = 'moments ago';
            }

            return $r;
        }
    }

PHP:

Thanks in advance

 

} elseif($difference >= 60*60*24){      // if more than a day ago
   $int = intval($difference / (60*60*24));
   if ($int == 1) {
      $r = 'Yesterday';
   } else {
      $r = $int . ' days ago';
   }
}

PHP:

 

Works just perfect, thanks!!!