diff --git a/collects/racket/private/string.rkt b/collects/racket/private/string.rkt
index ca3c6255ed..b4e7b0f3f8 100644
--- a/collects/racket/private/string.rkt
+++ b/collects/racket/private/string.rkt
@@ -404,7 +404,7 @@
                                                              (check
                                                               replacement
                                                               (for/list ([m ms])
-                                                                (sub buf (car m) (cdr m))))
+                                                                (and m (sub buf (car m) (cdr m)))))
                                                              (replac ms replacement))
                                                          (sub buf start mstart)
                                                          acc))
diff --git a/collects/tests/racket/basic.rktl b/collects/tests/racket/basic.rktl
index 97ea6a7212..fc94c7c8c4 100644
--- a/collects/tests/racket/basic.rktl
+++ b/collects/tests/racket/basic.rktl
@@ -1090,6 +1090,8 @@
          ((equal? what #"trout") (bytes-append color #" fish"))
          (else (bytes-append color #" " what)))))
 
+(test "foofoo" regexp-replace* #px"(.)?" "a" (lambda args "foo"))
+
 ;; Test weird port offsets:
 (define (test-weird-offset regexp-match regexp-match-positions)
   (test #f regexp-match "e" (open-input-string ""))