diff --git a/pkgs/racket-pkgs/racket-test/tests/racket/chaperone.rktl b/pkgs/racket-pkgs/racket-test/tests/racket/chaperone.rktl
index 9252a64fa2..80df4dcc9a 100644
--- a/pkgs/racket-pkgs/racket-test/tests/racket/chaperone.rktl
+++ b/pkgs/racket-pkgs/racket-test/tests/racket/chaperone.rktl
@@ -1510,7 +1510,12 @@
 
 (let ()
   (struct s ([a #:mutable]))
-  (err/rt-test (impersonate-struct 5 set-s-a! (lambda (a b) b))))
+  (err/rt-test (impersonate-struct 5 set-s-a! (lambda (a b) b)))
+  (err/rt-test (impersonate-struct (s 1) #f (λ (a b) v))
+               (λ (x) 
+                 (and (exn:application:type? x)
+                      (regexp-match #rx"struct-type-property-accessor-procedure[?]" 
+                                    (exn-message x))))))
 
 ;; ----------------------------------------
 
diff --git a/racket/src/racket/src/struct.c b/racket/src/racket/src/struct.c
index 01f6b61328..6ad1c72a9e 100644
--- a/racket/src/racket/src/struct.c
+++ b/racket/src/racket/src/struct.c
@@ -5473,10 +5473,10 @@ static Scheme_Object *do_chaperone_struct(const char *name, int is_impersonator,
       offset = -2;
     } else {
       scheme_wrong_contract(name, 
-                            (is_impersonator
-                             ? "(or/c struct-accessor-procedure? struct-mutator-procedure?)"
-                             : ("(or/c struct-accessor-procedure? struct-mutator-procedure?"
-                                " struct-type-property-accessor-procedure? (one-of/c struct-info))")),
+                            "(or/c struct-accessor-procedure?\n"
+			    "      struct-mutator-procedure?\n"
+                            "      struct-type-property-accessor-procedure?\n"
+			    "      (one-of/c struct-info))",
                             i, argc, argv);
       return NULL;
     }