diff --git a/usr/local/www/system_usermanager_settings.php b/usr/local/www/system_usermanager_settings.php
index 274a359c68..352d5cc781 100755
--- a/usr/local/www/system_usermanager_settings.php
+++ b/usr/local/www/system_usermanager_settings.php
@@ -65,7 +65,7 @@ if ($_POST) {
 
 	if (!$input_errors) {
 
-		if(isset($_POST['session_timeout']))
+		if(isset($_POST['session_timeout']) && $_POST['session_timeout'] != "")
 			$config['system']['webgui']['session_timeout'] = intval($_POST['session_timeout']);
 		else
 			unset($config['system']['webgui']['session_timeout']);