diff --git a/collects/redex/examples/racket-machine/model-impl.rkt b/collects/redex/examples/racket-machine/model-impl.rkt
index 0c74b52be2..6eb384b954 100644
--- a/collects/redex/examples/racket-machine/model-impl.rkt
+++ b/collects/redex/examples/racket-machine/model-impl.rkt
@@ -63,7 +63,7 @@
         `(branch ,(recur c) ,(recur t) ,(recur e))]
        [(let-rec rs b)
         `(let-rec ,(map recur rs) ,(recur b))]
-       [(lam _ _ _ τs #f ns `(val/ref ...) _ b)
+       [(lam _ _ _ τs #f ns `(val/ref ...) _ _ b)
         `(lam ,τs ,(vector->list ns) ,(recur b))]
        [(closure l _)
         (define (model-rep)
@@ -122,7 +122,7 @@
               [(let-rec rs b)
                (for-each recur rs) 
                (recur b)]
-              [(lam _ _ _ _ _ _ _ _ b)
+              [(lam _ _ _ _ _ _ _ _ _ b)
                (recur b)]
               [(closure l _)
                (recur l)]