Download a file named with an apostrophe using PHP

I'm trying to modify a well know script for downloading files - to allow a filename with an apostrophe in it's name... such as [Fred's file.mp3] - These files must contain an apostrophe to make sense. Is there a workaround for this?

If the filename has an apostrophe, the script just does nothing.

Here's the code snippet:

if($_GET['download'] && $forcedownloads) {
$file = str_replace('/', '', $_GET['download']);
$file = str_replace('..', '', $file);

if(file_exists($leadon . $file)) {
header("Content-type: application/x-download");
header("Content-Length: ".filesize($leadon . $file));
header('Content-Disposition: attachment; filename="'.$file.'"');
readfile($leadon . $file);
die();
}
}