解析XML / RSS时，由于某种原因删除了斜杠

Question

I got this function to go trough a RSS feed and output the data.

function parseRSS($xml) {
$max = 6;
     for($i=0; $i<$max; $i++) {
          $url = $xml->channel->item[$i]->link;
          $title = $xml->channel->item[$i]->title;  
          echo '<li><a href="'.$url.'">'.$title.'</a></li>';
     }
}

For some reason, the $url outputs a domain like this: http:/www.domain.com/blabla

(notice the missing double // after http:)

I double checked the source and the links are alright there, just while outputting (for some reason) one slash is removed.

Anyone got a clue what causes this and how it can be solved? (I was thinking of using str_replace and replacing http:/ by http:// before echoing, anyone a clue on how to do that?)