diff --git a/libguile/continuations.c b/libguile/continuations.c
index e5c8c0210..c9da124d8 100644
--- a/libguile/continuations.c
+++ b/libguile/continuations.c
@@ -134,6 +134,7 @@ scm_make_continuation (int *first)
 #if ! SCM_STACK_GROWS_UP
   src -= stack_size;
 #endif
+  continuation->offset = continuation->stack - src;
   memcpy (continuation->stack, src, sizeof (SCM_STACKITEM) * stack_size);
 
 #ifdef __ia64__
diff --git a/libguile/continuations.h b/libguile/continuations.h
index 6f0982033..d1298c22d 100644
--- a/libguile/continuations.h
+++ b/libguile/continuations.h
@@ -55,8 +55,19 @@ typedef struct
   size_t num_stack_items;   /* size of the saved stack.  */
   unsigned long seq;        /* dynamic root identifier.  */
 
-  /* the most recently created debug frame on the live stack, before
-     it was saved.  */
+  /* The offset from the live stack location and this copy.  This is
+     used to adjust pointers from within the copied stack to the stack
+     itself.
+
+     Thus, when you read a pointer from the copied stack that points
+     into the live stack, you need to add OFFSET so that it points
+     into the copy.
+  */
+  scm_t_ptrdiff offset;
+
+  /* The most recently created debug frame on the live stack, before
+     it was saved.  This need to be adjusted with OFFSET, above.
+  */
   struct scm_t_debug_frame *dframe;
 
   SCM_STACKITEM stack[1];    /* copied stack of size num_stack_items.  */