I've written the Perl script below which generates a warning and I can't work out why.

```
#!/usr/local/bin/perl -w

$status = $ENV{ 'STATUS' };
if ( $status eq "" )
{
    $status = 0;
}
else
{
    $status = 1;
}

```

It says "`Use of uninitialized value in string eq at ./x.pl line 4.`"

Line 4 is the "`if ( $status eq "" )`" line, but the variable was initialised...

How can I get rid of this warning?