diff --git a/api/src/Preferences.php b/api/src/Preferences.php
index c9ce6286b4..81585d556f 100644
--- a/api/src/Preferences.php
+++ b/api/src/Preferences.php
@@ -421,7 +421,7 @@ class Preferences
 				default:
 					foreach($values as $app => $vals)
 					{
-						$this->group[$app] = $vals + (array)$this->group[$app];
+						$this->group[$app] = (array)$vals + (array)$this->group[$app];
 					}
 					break;
 			}