# OLD:$text =~ s/(?!\n)[^\x00-\x1f]//g;
$text =~ s/[^\x00-\x1f](?<!\n)//g; # (Can't use + now)

# or (if you need to exclude another character,
# let's say \n and \r

# OLD:$text =~ s/(?![\r\n])[^\x00-\x1f]//g;
$text =~ s/[^\x00-\x1f](?<![\r\n])//g;

# Note: it's usually better to avoid \r and \n and use
# literals like \cM and \cJ or \015, \012 or \x0d, \x0a.