diff --git a/collects/racket/private/string.rkt b/collects/racket/private/string.rkt
index b4e7b0f3f8..4121fe9076 100644
--- a/collects/racket/private/string.rkt
+++ b/collects/racket/private/string.rkt
@@ -87,14 +87,14 @@
           (or (hash-ref t key #f)
               (let ([rx* (run-tweak)]) (hash-set! t key rx*) rx*))))))
 
-  (define (regexp-try-match pattern input-port [start-k 0] [end-k #f] [out #f])
+  (define (regexp-try-match pattern input-port [start-k 0] [end-k #f] [out #f] [prefix #""])
     (unless (input-port? input-port)
       (raise-type-error 'regexp-try-match
                         "input port" input-port))
     (unless (or (not out) (output-port? out))
       (raise-type-error 'regexp-try-match
                         "output port or #f" out))
-    (let ([m (regexp-match-peek-positions pattern input-port start-k end-k)])
+    (let ([m (regexp-match-peek-positions pattern input-port start-k end-k #f prefix)])
       (and m
            ;; What happens if someone swipes our bytes before we can get them?
            (let ([drop (caar m)])
diff --git a/collects/tests/racket/string-mzlib.rktl b/collects/tests/racket/string-mzlib.rktl
index 2a5c20d640..b0c6406c79 100644
--- a/collects/tests/racket/string-mzlib.rktl
+++ b/collects/tests/racket/string-mzlib.rktl
@@ -39,6 +39,18 @@
   (test #f regexp-match/fail-without-reading #rx"hello there!!!" s)
   (test "hello there" read-string 50 s))
 
+;; Check remaining `regexp-match/fail-without-reading' arguments
+(let ([s (open-input-string "hello there")]
+      [o (open-output-bytes)])
+  (test #f regexp-match/fail-without-reading #rx"not there" s 0 5 o)
+  (test #"" get-output-bytes o)
+  (test #f regexp-match/fail-without-reading #rx"^hello" s 1 #f o)
+  (test #"" get-output-bytes o)
+  (test #f regexp-match/fail-without-reading #rx"^hello" s 0 #f o #"_")
+  (test #"" get-output-bytes o)
+  (test '(#"ello") regexp-match/fail-without-reading #rx"ello" s 0 #f o)
+  (test #"h" get-output-bytes o))
+
 (let ([g->re-test
        (lambda (glob . more)
          (let ([re (apply glob->regexp glob more)])