diff --git a/pkgs/gui-pkgs/gui-doc/scribblings/gui/menu-item-class.scrbl b/pkgs/gui-pkgs/gui-doc/scribblings/gui/menu-item-class.scrbl
index 827d1d0b..b3e57dcc 100644
--- a/pkgs/gui-pkgs/gui-doc/scribblings/gui/menu-item-class.scrbl
+++ b/pkgs/gui-pkgs/gui-doc/scribblings/gui/menu-item-class.scrbl
@@ -15,8 +15,9 @@ A @racket[menu-item%] is a plain string-labelled menu item. Its
                  [help-string (or/c label-string? #f) #f]
                  [demand-callback ((is-a?/c menu-item%) . -> . any) 
                            (lambda (i) (void))]
-                 [shortcut-prefix (listof (or/c 'alt 'cmd 'meta 'ctl 
-                                                'shift 'option)) 
+                 [shortcut-prefix (and/c (listof (or/c 'alt 'cmd 'meta 'ctl 
+                                                       'shift 'option))
+                                         (λ (x) (equal? x (remove-duplicates x))))
                                   (get-default-shortcut-prefix)])]{
 
 Creates a new menu item in @racket[parent]. The item is initially
diff --git a/pkgs/gui-pkgs/gui-doc/scribblings/gui/miscwin-funcs.scrbl b/pkgs/gui-pkgs/gui-doc/scribblings/gui/miscwin-funcs.scrbl
index 0dfec35b..9a4d0fe5 100644
--- a/pkgs/gui-pkgs/gui-doc/scribblings/gui/miscwin-funcs.scrbl
+++ b/pkgs/gui-pkgs/gui-doc/scribblings/gui/miscwin-funcs.scrbl
@@ -96,9 +96,11 @@ The result depends on @racket[what], and a @racket[#f] result is only
 
 }
 
-
 @defproc[(get-default-shortcut-prefix)
-         (listof (or/c 'alt 'cmd 'meta 'ctl 'shift 'option))]{
+         (case (system-type)
+           [(windows) (list/c 'ctl)]
+           [(macosx)  (list/c 'cmd)]
+           [(unix)    (list/c (or/c 'alt 'cmd 'meta 'ctl 'shift 'option))])]{
 Returns an immutable list specifying the default prefix for menu
 shortcuts. See also
 @xmethod[selectable-menu-item<%> get-shortcut-prefix].