private function updateMessage()
    {
        $this->message = $this->_message;

        if (null !== $this->_source && null !== $this->_seek) {
            $this->message .= sprintf(' in %s at %d.', $this->_source, $this->_seek);
        } elseif (null !== $this->_source) {
            $this->message .= sprintf(' : %s.', $this->_source);
        }

        return $this;
    }