protected function _cleanupOldFiles(Model $model, array $fields) {
        $columns = $this->_columns[$model->alias];
        $data = $this->_doFind($model, array($model->alias . '.' . $model->primaryKey => $model->id));

        if (empty($data[$model->alias])) {
            return;
        }

        foreach ($fields as $column => $value) {
            if (empty($data[$model->alias][$column])) {
                continue;
            }

            if (!empty($this->settings[$model->alias][$columns[$column]])) {
                $attachment = $this->_settingsCallback($model, $this->settings[$model->alias][$columns[$column]]);

                if (!$attachment['cleanup']) {
                    continue;
                }
            }

            // Delete if previous value doesn't match new value
            $previous = $data[$model->alias][$column];

            if ($previous !== $value) {
                $this->_deleteFile($model, $columns[$column], $previous, $column);
            }
        }
    }