diff --git a/os2-timer.rkt b/os2-timer.rkt
index c26c014..d0b69a1 100644
--- a/os2-timer.rkt
+++ b/os2-timer.rkt
@@ -6,6 +6,7 @@
 ;; correct linear use of the various pointers.
 
 (require data/heap)
+(require racket/set)
 (require racket/match)
 (require "os2.rkt")
 
@@ -84,7 +85,8 @@
 ;; events and back.
 (define (timer-driver self-id)
   (transition (driver-state self-id (make-timer-heap))
-    (role 'relay-down (topic-subscriber (set-timer (wild) (wild) (wild)))
+    (role 'relay-down (set (topic-subscriber (set-timer (wild) (wild) (wild)))
+			   (topic-publisher (timer-expired (wild) (wild))))
       #:state state
       [(set-timer label msecs 'relative)
        (install-timer! state label (+ (current-inexact-milliseconds) msecs))]
@@ -123,7 +125,8 @@
 	(transition (relay-state next-counter (hash-remove active-timers counter))
 	  (and (hash-has-key? active-timers counter)
 	       (send-message (timer-expired (hash-ref active-timers counter) now))))]))
-    (role 'relay-down (topic-subscriber (set-timer (wild) (wild) (wild)))
+    (role 'relay-down (set (topic-subscriber (set-timer (wild) (wild) (wild)))
+			   (topic-publisher (timer-expired (wild) (wild))))
       #:state (relay-state next-counter active-timers)
       [(set-timer label msecs kind)
        (transition (relay-state (+ next-counter 1) (hash-set active-timers next-counter label))