diff --git a/common.php b/common.php
index bc02fbed..2cce36c4 100644
--- a/common.php
+++ b/common.php
@@ -21,6 +21,13 @@ if(!defined('POSTFIXADMIN')) { # already defined if called from setup.php
 
     if (!defined('POSTFIXADMIN_CLI')) {
         session_start();
+
+        if (defined('POSTFIXADMIN_LOGOUT')) {
+            session_unset();
+            session_destroy();
+            session_start();
+        }
+
         if(empty($_SESSION['flash'])) {
             $_SESSION['flash'] = array();
         }
diff --git a/login.php b/login.php
index 3e68acc2..8b577e28 100644
--- a/login.php
+++ b/login.php
@@ -26,6 +26,7 @@
  *  lang
  */
 
+define('POSTFIXADMIN_LOGOUT', 1);
 require_once('common.php');
 
 if($CONF['configured'] !== true) {
diff --git a/users/login.php b/users/login.php
index bc2744e0..13ee14e5 100644
--- a/users/login.php
+++ b/users/login.php
@@ -27,6 +27,7 @@
  */
 
 $rel_path = '../';
+define('POSTFIXADMIN_LOGOUT', 1);
 require_once("../common.php");