diff --git a/pkgs/racket-test-core/tests/racket/prompt.rktl b/pkgs/racket-test-core/tests/racket/prompt.rktl
index 3a5e31de91..591cbcead3 100644
--- a/pkgs/racket-test-core/tests/racket/prompt.rktl
+++ b/pkgs/racket-test-core/tests/racket/prompt.rktl
@@ -464,6 +464,42 @@
     ;; let's check that 3/4 were collected:
     (test #t < (hash-count ht) (* 1/4 (length l)))))
 
+;;----------------------------------------
+;; Check that it works to apply a continuation that shares with
+;; an enclosing continuation, where a runstack overflow happens
+;; between the continuations
+
+(let ()
+  (define N 100)
+  (define N2 10)
+  (define M 10)
+
+  (define p (make-continuation-prompt-tag))
+
+  (define (grab n m k-prev q)
+    (cond
+     [(positive? n)
+      (let ([x (grab (sub1 n) m k-prev q)])
+        (lambda () x))]
+     [(positive? m)
+      ((call/cc
+        (lambda (k)
+          (grab N2 (sub1 m) k q))
+        p))]
+     [(positive? q)
+      (call-with-continuation-prompt
+       (lambda ()
+         (k-prev
+          (lambda ()
+            (grab N M void (sub1 q)))))
+       p)]
+     [else void]))
+
+  (call-with-continuation-prompt
+   (lambda ()
+     (grab N M void 10))
+   p))
+
 ;;----------------------------------------
 
 (report-errs)
diff --git a/racket/src/racket/src/fun.c b/racket/src/racket/src/fun.c
index 5ef923b721..32c8416e96 100644
--- a/racket/src/racket/src/fun.c
+++ b/racket/src/racket/src/fun.c
@@ -4793,6 +4793,8 @@ static Scheme_Saved_Stack *copy_out_runstack(Scheme_Thread *p,
     size = p->runstack_size - (runstack XFORM_OK_MINUS runstack_start);
   }
 
+  MZ_ASSERT(size <= p->runstack_size);
+
   saved->runstack_size = size;
   start = MALLOC_N(Scheme_Object*, size);
   saved->runstack_start = start;
@@ -5934,11 +5936,12 @@ static void restore_continuation(Scheme_Cont *cont, Scheme_Thread *p, int for_pr
       Scheme_Cont *rs_cont = cont;
       Scheme_Saved_Stack *saved, *actual;
       int delta = 0;
-      while (rs_cont->buf_ptr->buf.cont) {
+      while (rs_cont->buf_ptr->buf.cont
+             && (rs_cont->buf_ptr->buf.cont->runstack_start == cont->runstack_start)) {
         delta += rs_cont->runstack_copied->runstack_size;
         rs_cont = rs_cont->buf_ptr->buf.cont;
-        if (rs_cont->runstack_copied->runstack_size) {
-          delta -= 1; /* overlap for not-saved call/cc argument */
+        if (rs_cont->runstack_copied->runstack_size > MAX_CALL_CC_ARG_COUNT) {
+          delta -= MAX_CALL_CC_ARG_COUNT; /* overlap for not-saved call/cc argument */
         }
       }
       actual = NULL;
@@ -5954,6 +5957,7 @@ static void restore_continuation(Scheme_Cont *cont, Scheme_Thread *p, int for_pr
       } else {
         meta_prompt->runstack_boundary_start = MZ_RUNSTACK_START;
         meta_prompt->runstack_boundary_offset = (MZ_RUNSTACK - MZ_RUNSTACK_START) + saved->runstack_size + delta;
+        MZ_ASSERT(meta_prompt->runstack_boundary_offset <= scheme_current_thread->runstack_size);
       }
     }