diff --git a/core/actor.lisp b/core/actor.lisp
index 97455c1..3d2fcb5 100644
--- a/core/actor.lisp
+++ b/core/actor.lisp
@@ -18,6 +18,12 @@
 
 ;;;; basic message implementation
 
+(defgeneric content (msg)
+  (:method (msg) msg))
+
+(defgeneric customer (msg)
+  (:method (msg) nil))
+
 (defclass message ()
   ((content :reader content :initarg :content :initform nil)
    (customer :reader customer :initarg :customer :initform nil)))
@@ -39,7 +45,7 @@
       ch)))
 
 (defun stop (mb)
-  (send mb (message +quit-message+)))
+  (send mb +quit-message+))
 
 (defun ac-loop (mb bhv)
   (let ((msg (async:rcv mb)))