diff --git a/collects/tests/racket/optimize.rktl b/collects/tests/racket/optimize.rktl
index f15460c513..69d096b529 100644
--- a/collects/tests/racket/optimize.rktl
+++ b/collects/tests/racket/optimize.rktl
@@ -2573,5 +2573,14 @@
     (read (open-input-bytes (get-output-bytes o)))))
 
 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; check error checking of JITted `continuation-mark-set-first'
+
+(err/rt-test (let ([f #f])
+               (set! f (lambda ()
+                         (continuation-mark-set-first 5 #f)))
+               (f)))
+
+;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
 
 (report-errs)
diff --git a/src/racket/src/jitinline.c b/src/racket/src/jitinline.c
index 70afb2cf5d..b5b57b5fda 100644
--- a/src/racket/src/jitinline.c
+++ b/src/racket/src/jitinline.c
@@ -56,6 +56,15 @@ static Scheme_Object *extract_one_cc_mark_to_tag(Scheme_Object *mark_set,
 {
   /* wrapper on scheme_extract_one_cc_mark_to_tag() to convert NULL to false */
   Scheme_Object *r;
+
+  if (mark_set && !SAME_TYPE(SCHEME_TYPE(mark_set), scheme_cont_mark_set_type)) {
+    Scheme_Object *a[2];
+    a[0] = mark_set;
+    a[1] = key;
+    scheme_wrong_contract("continuation-mark-set-first", "(or/c continuation-mark-set? #f)", 0, 2, a);
+    return NULL;
+  }
+
   r = scheme_extract_one_cc_mark_to_tag(mark_set, key, prompt_tag);
   if (!r) return scheme_false;
   return r;