diff --git a/os2.rkt b/os2.rkt
index f6cb4a0..cb326e8 100644
--- a/os2.rkt
+++ b/os2.rkt
@@ -186,7 +186,7 @@
 (define (make-delete-role pre-eid [reason #f]) (delete-role pre-eid reason))
 (define (make-send-message body [role 'publisher]) (send-message body role))
 (define (make-spawn main [k #f]) (spawn main k))
-(define (make-kill [pid #f] [reason #f]) (kill pid reason))
+(define (make-kill [pid #f] #:reason [reason #f]) (kill pid reason))
 
 (define (extend-transition t . more-actions)
   (match t