Solve mailer.php error on contact.php page

[anthlasserre]

I can't send a mail from contact.php, by looking the apache error.log I have:
PHP Parse error: syntax error, unexpected '$this' (T_VARIABLE), expecting function (T_FUNCTION) in /srv/www/include/contact/mailer.php on line 167, referer: http://aptmirror/contact.php