diff --git a/examples/platformer/main.rkt b/examples/platformer/main.rkt
index c895264..918a836 100644
--- a/examples/platformer/main.rkt
+++ b/examples/platformer/main.rkt
@@ -920,7 +920,8 @@
 (define (spawn-standalone-assertions . patches)
   (<spawn> (lambda ()
              (list (lambda (e s) #f)
-                   (transition (void) (patch-seq* patches))))))
+                   (transition (void) (patch-seq* patches))
+                   #f))))
 
 (define (spawn-background-image level-size scene)
   (match-define (vector level-width level-height) level-size)