diff --git a/docs/simplesamlphp-install.txt b/docs/simplesamlphp-install.txt
index 95142748b5e1c75ee6434da6862c5c3b4ba42da6..3dcbf7d3ccfa656036beedb56466d5348733fe28 100644
--- a/docs/simplesamlphp-install.txt
+++ b/docs/simplesamlphp-install.txt
@@ -35,8 +35,7 @@ Prerequisites
  * Some webserver capable of executing PHP scripts.
  * PHP version >= 5.2.0.
  * Suppoort for the following PHP extensions:
-   * Always required: `date`, `dom`, `hash`, `libxml`, `openssl`, `pcre`, `SPL`, `zlib`
-   * When encrypting assertions: `mcrypt`
+   * Always required: `date`, `dom`, `hash`, `libxml`, `openssl`, `pcre`, `SPL`, `zlib`, `mcrypt`
    * When authenticating against LDAP server: `ldap`
    * When authenticating against RADIUS server: `radius`
    * When saving session information to memcache-server: `memcache`
diff --git a/modules/core/www/frontpage_config.php b/modules/core/www/frontpage_config.php
index 136b4afa1f21bcc9b400670b6b62a829fb0772aa..7f4eece2197823f2ba7667254818c21f25f2a514 100644
--- a/modules/core/www/frontpage_config.php
+++ b/modules/core/www/frontpage_config.php
@@ -85,7 +85,7 @@ $functionchecks = array(
 	'simplexml_import_dom' => array('required', 'SimpleXML'),
 	'dom_import_simplexml' => array('required', 'XML DOM'),
 	'preg_match'       => array('required',  'RegEx support'),
-	'mcrypt_module_open'=> array('optional',  'MCrypt'),
+	'mcrypt_module_open'=> array('required',  'MCrypt'),
 	'mysql_connect'    => array('optional',  'MySQL support'),
 );
 if (SimpleSAML_Module::isModuleEnabled('ldap')) {