diff --git a/pkgs/rackunit-pkgs/rackunit-lib/rackunit/private/check.rkt b/pkgs/rackunit-pkgs/rackunit-lib/rackunit/private/check.rkt
index 191de1990f..8b9539751e 100644
--- a/pkgs/rackunit-pkgs/rackunit-lib/rackunit/private/check.rkt
+++ b/pkgs/rackunit-pkgs/rackunit-lib/rackunit/private/check.rkt
@@ -205,7 +205,13 @@
               #t
               (fail-check)))))]))
 
+(define (raise-error-if-not-thunk name thunk)
+  (unless (and (procedure? thunk)
+               (procedure-arity-includes? thunk 0))
+    (raise-arguments-error name "thunk must be a procedure that accepts 0 arguments" "thunk" thunk)))
+
 (define-check (check-exn raw-pred thunk)
+  (raise-error-if-not-thunk 'check-exn thunk)
   (let ([pred (if (regexp? raw-pred)
                   (λ (x) (and (exn:fail? x) (regexp-match raw-pred (exn-message x))))
                   raw-pred)])
@@ -236,6 +242,7 @@
        (lambda () (fail-check))))))
 
 (define-check (check-not-exn thunk)
+  (raise-error-if-not-thunk 'check-not-exn thunk)
   (with-handlers
       ([exn:test:check?
         (lambda (exn) (refail-check exn))]
diff --git a/pkgs/rackunit-pkgs/rackunit-test/tests/rackunit/check-test.rkt b/pkgs/rackunit-pkgs/rackunit-test/tests/rackunit/check-test.rkt
index f790a6bbaa..8e7be6e82e 100644
--- a/pkgs/rackunit-pkgs/rackunit-test/tests/rackunit/check-test.rkt
+++ b/pkgs/rackunit-pkgs/rackunit-test/tests/rackunit/check-test.rkt
@@ -318,6 +318,32 @@
                    found?))
              #f names))))
    
+   ;; Verify that check-exn and check-not-exn raise errors (not check
+   ;; failures) if not given thunks.
+   (test-case
+    "check-exn raises contract exception if not given a procedure"
+    (check-exn exn:fail:contract?
+               (lambda ()
+                 (check-exn exn:fail? 'not-a-procedure))))
+
+   (test-case
+    "check-exn raises contract exception if given a procedure with incorrect arity"
+    (check-exn exn:fail:contract?
+               (lambda ()
+                 (check-exn exn:fail? (lambda (x) x)))))
+
+   (test-case
+    "check-not-exn raises contract exception if not given a procedure"
+    (check-exn exn:fail:contract?
+               (lambda ()
+                 (check-not-exn 'not-a-procedure))))
+
+   (test-case
+    "check-not-exn raises contract exception if given a procedure with incorrect arity"
+    (check-exn exn:fail:contract?
+               (lambda ()
+                 (check-not-exn (lambda (x) x)))))
+
    ;; Regression test
    ;; Uses of check (and derived forms) used to be un-compilable!
    ;; We check that (write (compile --code-using-check--)) works.