diff --git a/examples/platformer/game.rkt b/examples/platformer/game.rkt
index de91737..e99ec46 100644
--- a/examples/platformer/game.rkt
+++ b/examples/platformer/game.rkt
@@ -352,8 +352,8 @@
            (match e
              [(message (add-to-score delta))
               (transition (+ s delta)
-                          (retract (current-score ?))
-                          (assert (current-score delta)))]
+                          (patch-seq (retract (current-score ?))
+                                     (assert (current-score delta))))]
              [_ #f]))
          0
          (sub (add-to-score ?))))