diff --git a/pkgs/racket-test-core/tests/racket/file.rktl b/pkgs/racket-test-core/tests/racket/file.rktl
index 3a9e12c5a0..a00f172330 100644
--- a/pkgs/racket-test-core/tests/racket/file.rktl
+++ b/pkgs/racket-test-core/tests/racket/file.rktl
@@ -334,6 +334,11 @@
 (define tempfilename (make-temporary-file))
 (when (file-exists? tempfilename)
   (delete-file tempfilename))
+
+(err/rt-test (open-output-file tempfilename #:exists 'update) exn:fail:filesystem?)
+(test #t output-port? (open-output-file tempfilename #:exists 'can-update))
+(delete-file tempfilename)
+
 (let ([p (open-output-file tempfilename)])
   (err/rt-test (write-special 'foo p) exn:application:mismatch?)
   (test #t integer? (port-file-identity p))
diff --git a/racket/src/io/port/file-port.rkt b/racket/src/io/port/file-port.rkt
index 4cbd2b8607..8d7678aabc 100644
--- a/racket/src/io/port/file-port.rkt
+++ b/racket/src/io/port/file-port.rkt
@@ -63,8 +63,8 @@
                                       RKTIO_OPEN_CAN_EXIST)]
       [(must-truncate) (+ RKTIO_OPEN_TRUNCATE
                           RKTIO_OPEN_MUST_EXIST)]
-      [(update) RKTIO_OPEN_CAN_EXIST]
-      [(must-update) RKTIO_OPEN_MUST_EXIST]
+      [(can-update) RKTIO_OPEN_CAN_EXIST]
+      [(update) RKTIO_OPEN_MUST_EXIST]
       [(append) RKTIO_OPEN_APPEND]
       [else 0]))
   (define (mode? v)