diff --git a/pkgs/racket-test-core/tests/racket/list.rktl b/pkgs/racket-test-core/tests/racket/list.rktl
index 1a7adec316..55d1ca3e41 100644
--- a/pkgs/racket-test-core/tests/racket/list.rktl
+++ b/pkgs/racket-test-core/tests/racket/list.rktl
@@ -336,6 +336,9 @@
 (test 'a check-duplicate '(a a b))
 (test '(a 3) check-duplicate '((a 1) (b 2) (a 3)) #:key car)
 (test 4 check-duplicate '(1 2 3 4 5 6) (lambda (x y) (equal? (modulo x 3) (modulo y 3))))
+(err/rt-test (check-duplicate 'a))
+(err/rt-test (check-duplicate '(1) #f))
+(err/rt-test (check-duplicate '(1) #:key #f))
 
 ;; ---------- remove-duplicates ----------
 (let ()
diff --git a/racket/collects/racket/list.rkt b/racket/collects/racket/list.rkt
index c3745c6c00..b0ffde536b 100644
--- a/racket/collects/racket/list.rkt
+++ b/racket/collects/racket/list.rkt
@@ -355,6 +355,11 @@
 (define (check-duplicate items
                          [same? equal?]
                          #:key [key values])
+  (unless (list? items)
+    (raise-argument-error 'check-duplicate "list?" items))
+  (unless (and (procedure? key)
+               (procedure-arity-includes? key 1))
+    (raise-argument-error 'check-duplicate "(-> any/c any/c)" key))
   (cond [(eq? same? equal?)
          (check-duplicate/t items key (make-hash))]
         [(eq? same? eq?)
@@ -362,6 +367,11 @@
         [(eq? same? eqv?)
          (check-duplicate/t items key (make-hasheqv))]
         [else
+         (unless (and (procedure? same?)
+                      (procedure-arity-includes? same? 2))
+           (raise-argument-error 'check-duplicate
+                                 "(any/c any/c . -> . any/c)"
+                                 same?))
          (check-duplicate/list items key same?)]))
 (define (check-duplicate/t items key table)
   (let loop ([items items])