Kan man kun tillade upload af specifik fil..??

Jeg harfundet dette script på nettet og kunne godt tænke mig at vide man kan gøre således at det kun er en specifik fil der kan uploades. Altså det skal ikke bare være en bestemt type men også en bestemt navn: (rigtignavn.gif)

<?php
$target = "upload/";
$target = $target . basename( $_FILES['uploaded']['name']) ;
$ok=1;

//This is our size condition
if ($uploaded_size > 350000)
{
echo "Your file is too large.<br>";
$ok=0;
}

//This is our limit file type condition
if ($uploaded_type =="image/gif")
{
echo "No PHP files<br>";
$ok=0;
}

//Here we check that $ok was not set to 0 by an error
if ($ok==0)
{
Echo "Sorry your file was not uploaded";
}

//If everything is ok we try to upload it
else
{
if(move_uploaded_file($_FILES['uploaded']['tmp_name'], $target))
{
echo "The file ". basename( $_FILES['uploadedfile']['name']). " has been uploaded";
}
else
{
echo "Sorry, there was a problem uploading your file.";
}
}
?>