diff --git a/core-bundle/src/Resources/contao/dca/tl_settings.php b/core-bundle/src/Resources/contao/dca/tl_settings.php
index 89df869744d..b55a69ad0da 100644
--- a/core-bundle/src/Resources/contao/dca/tl_settings.php
+++ b/core-bundle/src/Resources/contao/dca/tl_settings.php
@@ -285,7 +285,7 @@
 		(
 			'label'                   => &$GLOBALS['TL_LANG']['tl_settings']['sessionTimeout'],
 			'inputType'               => 'text',
-			'eval'                    => array('mandatory'=>true, 'rgxp'=>'natural', 'minlength'=>3, 'nospace'=>true, 'tl_class'=>'w50')
+			'eval'                    => array('mandatory'=>true, 'rgxp'=>'natural', 'minlength'=>3, 'maxlength'=>7, 'nospace'=>true, 'tl_class'=>'w50')
 		),
 		'autologin' => array
 		(