diff --git a/src/ZM/Utils/SingletonTrait.php b/src/ZM/Utils/SingletonTrait.php
index a6649b61..1639fe83 100644
--- a/src/ZM/Utils/SingletonTrait.php
+++ b/src/ZM/Utils/SingletonTrait.php
@@ -11,6 +11,8 @@ trait SingletonTrait
      */
     private static $instance;
 
+    protected static $cached = [];
+
     /**
      * @return self
      */