diff --git a/os-big-bang-testing.rkt b/os-big-bang-testing.rkt
index d6cd732..091d447 100644
--- a/os-big-bang-testing.rkt
+++ b/os-big-bang-testing.rkt
@@ -6,11 +6,16 @@
 
 (provide check-message-handler)
 
+(define (flatten-transition t)
+  (if (transition? t)
+      (transition (transition-state t) (transition-actions t)) ;; autoflattens
+      (transition t '()))) ;; wrap for convenient comparison
+
 (define (check-message-handler mh initial-w message final-w expected-actions)
   (match-define (on-message pattern handler) mh)
   (check-true (pattern message) "Message-handler pattern did not match message provided")
   (define v (match (handler message initial-w)
 	      [(? transition? t) t]
 	      [new-w (transition new-w '())]))
-  (check-equal? v (transition final-w expected-actions)
+  (check-equal? (flatten-transition v) (transition final-w expected-actions)
 		"Produced world-and-actions did not match expected world-and-actions"))