diff --git a/racket/src/cs/rumble/bytes.ss b/racket/src/cs/rumble/bytes.ss
index 8b88c21d31..baf41a5b1b 100644
--- a/racket/src/cs/rumble/bytes.ss
+++ b/racket/src/cs/rumble/bytes.ss
@@ -147,7 +147,7 @@
         c))]
    [(a)
     (check who bytes? a)
-    (#2%bytevector-copy a)]
+    (#3%bytevector-copy a)]
    [() #vu8()]
    [args
     (let* ([size (let loop ([args args])
diff --git a/racket/src/cs/rumble/error.ss b/racket/src/cs/rumble/error.ss
index 501380ac8d..9e5e2d9380 100644
--- a/racket/src/cs/rumble/error.ss
+++ b/racket/src/cs/rumble/error.ss
@@ -682,6 +682,9 @@
                     (string=? "attempt to assign undefined variable ~s" (condition-message v))))
            (lambda (msg marks)
              (|#%app| exn:fail:contract:variable msg marks (car (condition-irritants v))))]
+          [(and (format-condition? v)
+                (string-prefix? "~?.  Some debugging context lost" (condition-message v)))
+           exn:fail]
           [else
            exn:fail:contract])
          (exn->string v)
diff --git a/racket/src/cs/rumble/procedure.ss b/racket/src/cs/rumble/procedure.ss
index 49a8f92ac8..684084eb79 100644
--- a/racket/src/cs/rumble/procedure.ss
+++ b/racket/src/cs/rumble/procedure.ss
@@ -37,18 +37,18 @@
   (case-lambda
     [(proc args)
      (if (#%procedure? proc)
-         (chez:apply proc args)
-         (chez:apply (extract-procedure proc (length args)) args))]
+         (#2%apply proc args)
+         (#2%apply (extract-procedure proc (length args)) args))]
     [(proc)
      (raise-arity-error 'apply (|#%app| arity-at-least 2) proc)]
     [(proc . argss)
      (if (#%procedure? proc)
-         (chez:apply chez:apply proc argss)
+         (#2%apply #2%apply proc argss)
          (let ([len (let loop ([argss argss])
                       (cond
                        [(null? (cdr argss)) (length (car argss))]
                        [else (fx+ 1 (loop (cdr argss)))]))])
-           (chez:apply chez:apply (extract-procedure proc len) argss)))]))
+           (#2%apply #2%apply (extract-procedure proc len) argss)))]))
 
 ;; See copy in "expander.sls"
 (define-syntax (|#%app| stx)