From perlop:

 The character "-" is treated specially and therefore "\-" is treated 
+as a literal "-".
[download]

The - indicates a range.

if($data !~ /^[\ \-\~\007\012\015\035\036\037]*$/) {
    $data =~ tr/[\ \-\~\007\012\015\035\036\037]/ /cs;
}
[download]

is probably what you need.