diff --git a/library/ajax/change_user_opt.php b/library/ajax/change_user_opt.php
index c5ab0fbf1..db9fc94e8 100644
--- a/library/ajax/change_user_opt.php
+++ b/library/ajax/change_user_opt.php
@@ -5,7 +5,7 @@ if (!defined('IN_AJAX')) die(basename(__FILE__));
 global $bf, $lang;
 
 $user_id = (int) $this->request['user_id'];
-$new_opt = Zend\Json\Json::decode($this->request['user_opt']);
+$new_opt = Zend\Json\Json::decode($this->request['user_opt'], Zend\Json\Json::TYPE_ARRAY);
 
 if (!$user_id OR !$u_data = get_userdata($user_id))
 {
diff --git a/library/includes/sessions.php b/library/includes/sessions.php
index a7e5b62c0..48290e10b 100644
--- a/library/includes/sessions.php
+++ b/library/includes/sessions.php
@@ -671,7 +671,7 @@ class user_common
 		}
 		else if (!empty($_COOKIE['opt_js']))
 		{
-			$opt_js = Zend\Json\Json::decode($_COOKIE['opt_js']);
+			$opt_js = Zend\Json\Json::decode($_COOKIE['opt_js'], Zend\Json\Json::TYPE_ARRAY);
 
 			if (is_array($opt_js))
 			{