diff --git a/ChangeLog b/ChangeLog
index 6541a95a2..e89bc01dd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -7,6 +7,7 @@ $HeadURL$
 
 2007-02-14 Marc Delisle  <lem9@users.sourceforge.net>
     * libraries/common.lib.php: white page after uploading a 700 Kio BLOB
+    * add a warning on main page if mcrypt can't be loaded (bug 1658160)
 
 2007-02-13 Sebastian Mendel <cybot_tm@users.sourceforge.net>
     * libaries/PMA_Sql.class.php: added much more functionality
diff --git a/libraries/auth/cookie.auth.lib.php b/libraries/auth/cookie.auth.lib.php
index 881a8f945..88788ee77 100644
--- a/libraries/auth/cookie.auth.lib.php
+++ b/libraries/auth/cookie.auth.lib.php
@@ -22,6 +22,8 @@ if (function_exists('mcrypt_encrypt') || PMA_dl('mcrypt')) {
     require_once './libraries/mcrypt.lib.php';
 } else {
     require_once './libraries/blowfish.php';
+    // for main.php:
+    define('PMA_WARN_FOR_MCRYPT',1);
 }
 
 
diff --git a/main.php b/main.php
index bd2f6c880..bb4fb14ad 100644
--- a/main.php
+++ b/main.php
@@ -394,6 +394,10 @@ if (defined('PMA_MYSQL_INT_VERSION') && PMA_MYSQL_INT_VERSION < 32332) {
     echo '<div class="warning">' . sprintf($strUpgrade, 'MySQL', '3.23.32') . '</div>' . "\n";
 }
 
+if (defined('PMA_WARN_FOR_MCRYPT')) {
+    echo '<div class="warning">' . PMA_sanitize(sprintf($strCantLoad, 'mcrypt')) . '</div>' . "\n";
+}
+
 /**
  * prints list item for main page
  *