public function setMasterFiles(array $masterFiles)
    {
        $this->_specificOptions['master_file']  = null; // to keep a compatibility
        $this->_specificOptions['master_files'] = null;
        $this->_masterFile_mtimes = array();

        clearstatcache();
        $i = 0;
        foreach ($masterFiles as $masterFile) {
            if (file_exists($masterFile)) {
                $mtime = filemtime($masterFile);
            } else {
                $mtime = false;
            }

            if (!$this->_specificOptions['ignore_missing_master_files'] && !$mtime) {
                Zend_Cache::throwException('Unable to read master_file : ' . $masterFile);
            }

            $this->_masterFile_mtimes[$i] = $mtime;
            $this->_specificOptions['master_files'][$i] = $masterFile;
            if ($i === 0) { // to keep a compatibility
                $this->_specificOptions['master_file'] = $masterFile;
            }

            $i++;
        }
    }