diff --git a/pkgs/racket-test-core/tests/racket/prompt-tests.rktl b/pkgs/racket-test-core/tests/racket/prompt-tests.rktl
index 888706338e..cc2d0f1d1c 100644
--- a/pkgs/racket-test-core/tests/racket/prompt-tests.rktl
+++ b/pkgs/racket-test-core/tests/racket/prompt-tests.rktl
@@ -1129,6 +1129,55 @@
                (test #t continuation-mark-set-first #f 'n)
                (loop (sub1 n)))))))))
 
+(let ()
+  (define (check call-with-ignored-composable-continuation)
+    ;; Caputured replacing installed with nested metacontinuations
+    (let ([k (call-with-continuation-prompt
+              (lambda ()
+                (with-continuation-mark
+                 'x
+                 71
+                 (call-with-ignored-composable-continuation
+                  (lambda (k2)
+                    (non-tail
+                     (with-continuation-mark
+                      'x
+                      72
+                      ((call-with-composable-continuation
+                        (lambda (k)
+                          (lambda () k)))))))))))])
+      (test '(72 71)
+            'nested-mc
+            (with-continuation-mark
+             'x 81
+             (k (lambda ()
+                  (continuation-mark-set->list (current-continuation-marks) 'x))))))
+
+    ;; Captured not replacing
+    (let ([k (call-with-continuation-prompt
+              (lambda ()
+                (non-tail
+                 (with-continuation-mark
+                  'x
+                  71
+                  (call-with-ignored-composable-continuation
+                   (lambda (k2)
+                     (non-tail
+                      (with-continuation-mark
+                       'x
+                       72
+                       ((call-with-composable-continuation
+                         (lambda (k)
+                           (lambda () k))))))))))))])
+      (test '(72 71 81)
+            'nested-mc
+            (with-continuation-mark
+             'x 81
+             (k (lambda ()
+                  (continuation-mark-set->list (current-continuation-marks) 'x)))))))
+  (check call-with-composable-continuation)
+  (check (lambda (proc) (proc #f))))
+
 ;; ----------------------------------------
 ;; Olivier Danvy's traversal
 
diff --git a/racket/src/racket/src/fun.c b/racket/src/racket/src/fun.c
index 2ecc783a79..a8de261f6c 100644
--- a/racket/src/racket/src/fun.c
+++ b/racket/src/racket/src/fun.c
@@ -5368,9 +5368,9 @@ void prune_cont_marks(Scheme_Meta_Continuation *resume_mc, Scheme_Cont *cont, Sc
     return;
   }
 
-  for (pos = cont->cont_mark_total, num_coverlap = 0;
-       pos--;
-       num_coverlap++) {
+  for (pos = 0, num_coverlap = 0;
+       pos < cont->cont_mark_total;
+       num_coverlap++, pos++) {
     if (cont->cont_mark_stack_copied[pos].pos != (cont->cont_mark_pos_bottom + 2))
       break;
   }
@@ -5399,7 +5399,7 @@ void prune_cont_marks(Scheme_Meta_Continuation *resume_mc, Scheme_Cont *cont, Sc
       scheme_hash_set(ht, SCHEME_VEC_ELS(extra_marks)[i], val);
     }
   }
-  for (pos = cont->cont_mark_total - 1, i = 0; i < num_coverlap; i++, pos--) {
+  for (pos = 0, i = 0; i < num_coverlap; i++, pos++) {
     scheme_hash_set(ht, 
                     cont->cont_mark_stack_copied[pos].key,
                     NULL);
@@ -8456,10 +8456,6 @@ scheme_extract_one_cc_mark_with_meta(Scheme_Object *mark_set, Scheme_Object *key
     while (chain) {
       if (chain->key == key)
         if (key_arg != key)
-          /*
-           * TODO: is this the only name that this procedure is called as
-           * publicly?
-           */
           return scheme_chaperone_do_continuation_mark("continuation-mark-set-first",
                                                        1, key_arg, chain->val);
         else