diff --git a/lib/kolab_sync_logger.php b/lib/kolab_sync_logger.php
index 00ec254..e6b8ec3 100644
--- a/lib/kolab_sync_logger.php
+++ b/lib/kolab_sync_logger.php
@@ -1,212 +1,212 @@
 <?php
 
 /*
  +--------------------------------------------------------------------------+
  | Kolab Sync (ActiveSync for Kolab)                                        |
  |                                                                          |
  | Copyright (C) 2011-2012, Kolab Systems AG                                |
  |                                                                          |
  | This program is free software: you can redistribute it and/or modify     |
  | it under the terms of the GNU Affero General Public License as published |
  | by the Free Software Foundation, either version 3 of the License, or     |
  | (at your option) any later version.                                      |
  |                                                                          |
  | This program is distributed in the hope that it will be useful,          |
  | but WITHOUT ANY WARRANTY; without even the implied warranty of           |
  | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the             |
  | GNU Affero General Public License for more details.                      |
  |                                                                          |
  | You should have received a copy of the GNU Affero General Public License |
  | along with this program. If not, see <http://www.gnu.org/licenses/>      |
  +--------------------------------------------------------------------------+
  | Author: Aleksander Machniak <machniak@kolabsys.com>                      |
  +--------------------------------------------------------------------------+
 */
 
 /**
  * Class for logging messages into log file(s)
  */
 class kolab_sync_logger extends Zend_Log
 {
     public $mode;
 
     protected $log_driver;
     protected $logfile;
     protected $format;
     protected $log_dir;
     protected $username;
 
     /**
      * Constructor
      */
     public function __construct($mode = null)
     {
         $rcube = rcube::get_instance();
 
         $this->mode    = intval($mode);
         $this->logfile = $rcube->config->get('activesync_log_file');
         $this->log_driver = $rcube->config->get('log_driver');
         $this->format  = $rcube->config->get('log_date_format', 'd-M-Y H:i:s O');
         $this->log_dir = $rcube->config->get('log_dir');
 
         $r = new ReflectionClass($this);
         $this->_priorities = $r->getConstants();
     }
 
     public function __call($method, $params)
     {
         $method = strtoupper($method);
         if ($this->_priorities[$method] <= $this->mode) {
             $this->log(array_shift($params), $method);
         }
     }
 
     /**
      * Check whether debug logging is enabled
      *
      * @return bool
      */
     public function hasDebug()
     {
         // This is what we check in self::log() below
         return !empty($this->log_dir) && $this->mode >= self::NOTICE;
     }
 
     /**
      * Message logger
      *
      * @param string     $message Log message
      * @param int|string $method  Message severity
      */
     public function log($message, $method, $extras = null)
     {
         if (is_numeric($method)) {
             $mode   = $method;
             $method = array_search($method, $this->_priorities);
         } else {
             $mode = $this->_priorities[$method];
         }
 
         // Don't log messages with lower prio than the configured one
         if ($mode > $this->mode) {
             return;
         }
 
         // Don't log debug messages if it's disabled e.g. by per_user_logging
         if (empty($this->log_dir) && $mode >= self::NOTICE) {
             return;
         }
 
         $rcube   = rcube::get_instance();
         $log_dir = $this->log_dir ?: $rcube->config->get('log_dir');
         $logfile = $this->logfile;
 
         // if log_file is configured all logs will go to it
         // otherwise use separate file for info/debug and warning/error
         $file = "undefined";
         if (!$logfile) {
             switch ($mode) {
                 case self::DEBUG:
                 case self::INFO:
                 case self::NOTICE:
                     $file = 'console';
                     break;
                 default:
                     $file = 'errors';
                     break;
             }
 
             $logfile = $log_dir . DIRECTORY_SEPARATOR . $file;
 
             if (version_compare(version_parse(RCUBE_VERSION), '1.4.0') >= 0) {
                 $logfile .= $rcube->config->get('log_file_ext', '.log');
             }
         } elseif ($logfile[0] != '/') {
             $logfile = $log_dir . DIRECTORY_SEPARATOR . $logfile;
         }
 
         if (!is_string($message)) {
             $message = var_export($message, true);
         }
 
         // write message in logfmt format with extra info when configured to log to STDOUT
         if ($this->log_driver == 'logfmt') {
             $user_name = $this->username;
 
             $output = "name=$file component=syncroton";
             $params = ['cmd' => 'Cmd', 'device' => 'DeviceId', 'type' => 'DeviceType'];
 
             foreach ($params as $key => $val) {
                 if ($val = $_GET[$val]) {
                     $output .= " $key=$val";
                 }
             }
 
             if (!empty($user_name)) {
                 $output .= " user=$user_name";
             }
             $line = json_encode($message);
             $output .= " log=$line\n";
             file_put_contents("php://stdout", $output, FILE_APPEND) !== false;
             return;
         }
 
         // add user/request information to the log
         if ($mode <= self::WARN) {
             $device = [];
             $params = ['cmd' => 'Cmd', 'device' => 'DeviceId', 'type' => 'DeviceType'];
 
             if (!empty($this->username)) {
                 $device['user'] = $this->username;
             }
 
             foreach ($params as $key => $val) {
-                if ($val = $_GET[$val]) {
-                    $device[$key] = $val;
+                if (isset($_GET[$val])) {
+                    $device[$key] = $_GET[$val];
                 }
             }
 
             if (!empty($device)) {
                 $message = @json_encode($device) . ' ' . $message;
             }
         }
 
         $date    = rcube_utils::date_format($this->format);
         $logline = sprintf("[%s]: [%s] %s\n", $date, $method, $message);
 
         // write message with file name when configured to log to STDOUT
         if ($this->log_driver == 'stdout') {
             $stdout = "php://stdout";
             file_put_contents($stdout, $logline, FILE_APPEND);
             return;
         }
 
         if ($fp = @fopen($logfile, 'a')) {
             fwrite($fp, $logline);
             fflush($fp);
             fclose($fp);
             return;
         }
 
         if ($mode <= self::WARN) {
             // send error to PHPs error handler if write to file didn't succeed
             trigger_error($message, E_USER_WARNING);
         }
     }
 
     /**
      * Set current user name to add into error log
      */
     public function set_username($username)
     {
         $this->username = $username;
     }
 
     /**
      * Set log directory
      */
     public function set_log_dir($dir)
     {
         $this->log_dir = $dir;
     }
 }