diff --git a/racket/src/cs/rumble/check.ss b/racket/src/cs/rumble/check.ss
index 48e11e9637..7a245a3a6a 100644
--- a/racket/src/cs/rumble/check.ss
+++ b/racket/src/cs/rumble/check.ss
@@ -45,9 +45,8 @@
        (and (integer? n)
             (exact? n)
             (not (negative? n))))
-     (with-syntax ([n-mask (bitwise-arithmetic-shift-left 1 (syntax->datum #'m))])
-       #'(lambda (p)
-           (unsafe-procedure-and-arity-includes? p n)))]))
+     #'(lambda (p)
+         (unsafe-procedure-and-arity-includes? p n))]))
 
 (define (check-space who what d-start d-len s-len)
   (unless (fx<= (fx+ d-start s-len) d-len)