diff --git a/html/main.php b/html/main.php
index a9f26ab05d0df2b6746a7d424828e2bf8f7fa550..bedec82dc198cf06411d8a2b5f545b95d30575ab 100644
--- a/html/main.php
+++ b/html/main.php
@@ -69,7 +69,7 @@ if (($config->get_cfg_value("forcessl") == "TRUE") && ($ssl != '')) {
   exit;
 }
 
-timezone::get_default_timezone();
+timezone::setDefaultTimezoneFromConfig();
 
 /* Check for invalid sessions */
 if (session::global_get('_LAST_PAGE_REQUEST') == "") {
diff --git a/include/class_config.inc b/include/class_config.inc
index 2d14b25ab1d0702c98edcd62a66b0898aa096354..b8ec47f86ea1f949d1ed6a8a0c9d6b2a236e8d40 100644
--- a/include/class_config.inc
+++ b/include/class_config.inc
@@ -448,6 +448,8 @@ class config  {
     session::global_set('DEBUGLEVEL', $debugLevel);
 
     IconTheme::loadThemes('themes');
+
+    timezone::setDefaultTimezoneFromConfig();
   }
 
 
diff --git a/include/class_timezone.inc b/include/class_timezone.inc
index 9c371b240309aa5c0854abf99ee724cf34d7964a..5758ec1511a7cc25f8e2f6c6387e3f0043eeb3f7 100644
--- a/include/class_timezone.inc
+++ b/include/class_timezone.inc
@@ -29,44 +29,60 @@
  * \brief This class contains all the function needed to manage the
  * timezones
  */
-class timezone {
+class timezone
+{
+  /*
+   * \brief This function sets the default timezone according to fusiondirectory configuration.
+   *
+   * \return TRUE upon success, FALSE otherwise
+   */
+  static public function setDefaultTimezoneFromConfig()
+  {
+    global $config;
+
+    /* Is there a timezone set in the fusiondirectory configuration */
+    if ($config->get_cfg_value('timezone') != '') {
+      $tz = $config->get_cfg_value('timezone');
+
+      if (@date_default_timezone_set($tz)) {
+        return TRUE;
+      } else {
+        msg_dialog::display(
+          _('Configuration error'),
+          sprintf(_('The timezone setting "%s" in your configuration is not valid.'), $tz),
+          ERROR_DIALOG
+        );
+      }
+    }
+    return FALSE;
+  }
 
   /*
    * \brief This function returns the offset for the default timezone.
    *
+   * deprecated
    * \param $stamp is used to detect summer or winter time.
-   * In case of PHP5, the integrated timezone functions are used.
    */
   static public function get_default_timezone($stamp = NULL)
   {
     global $config;
-    $tz = "";
-
-    /* Default return value if zone could not be detected */
-    $zone = array("name" => "unconfigured", "value" => 0);
 
     /* Use current timestamp if $stamp is not set */
     if ($stamp === NULL) {
       $stamp = time();
     }
 
-    /* Is there a timezone configured in the fusiondirectory configuration (fusiondirectory.conf) */
-    if ($config->get_cfg_value("timezone") != "") {
-      /* Get zonename */
-      $tz = $config->get_cfg_value("timezone");
-
-      if (!@date_default_timezone_set($tz)) {
-        msg_dialog::display(_("Configuration error"), sprintf(_("The timezone setting '%s' in your configuration is not valid. Cannot calculate correct timezone offset."), $tz), ERROR_DIALOG);
-      }
-      $tz_delta = date("Z", $stamp);
+    /* Is there a correct timezone set in the fusiondirectory configuration */
+    if (self::setDefaultTimezoneFromConfig()) {
+      $tz       = $config->get_cfg_value('timezone');
+      $tz_delta = date('Z', $stamp);
       $tz_delta = $tz_delta / 3600;
-      return array("name" => $tz, "value" => $tz_delta);
-
+      return array('name' => $tz, 'value' => $tz_delta);
+    } else {
+      return array('name' => 'unconfigured', 'value' => 0);
     }
-    return $zone;
   }
 
-
   /*
    * \brief Get the time zone informations
    *
@@ -76,5 +92,21 @@ class timezone {
   {
     return DateTimeZone::listIdentifiers();
   }
+
+  /* \brief Return default timezone as a DateTimeZone object */
+  static public function getDefaultTimeZone()
+  {
+    return new DateTimeZone(date_default_timezone_get());
+  }
+
+  /* \brief Return UTC timezone as a DateTimeZone object */
+  static public function utc()
+  {
+    static $utc;
+    if (!isset($utc)) {
+      $utc = new DateTimeZone('UTC');
+    }
+    return $utc;
+  }
 }
 ?>
diff --git a/plugins/personal/posix/class_posixAccount.inc b/plugins/personal/posix/class_posixAccount.inc
index e7be445703fc2ff09740a0f813cddbcee0b90583..3baedc3cfa309eb7795dcbb09d7d84eacdc33b5f 100644
--- a/plugins/personal/posix/class_posixAccount.inc
+++ b/plugins/personal/posix/class_posixAccount.inc
@@ -41,12 +41,12 @@ class EpochDaysDateAttribute extends DateAttribute
 
   protected function ldapToDate($ldapValue)
   {
-    $date = DateTime::createFromFormat('U', $ldapValue * self::$secondsPerDay, new DateTimeZone('UTC'));
+    $date = DateTime::createFromFormat('U', $ldapValue * self::$secondsPerDay, timezone::utc());
     if ($date !== FALSE) {
       return $date;
     } else {
       trigger_error('LDAP value for '.$this->getLdapName().' was not in the right date format.');
-      return new DateTime($ldapValue, new DateTimeZone('UTC'));
+      return new DateTime($ldapValue, timezone::utc());
     }
   }