diff --git a/piclib/prelude.scm b/piclib/prelude.scm
index 9b8a390a..7367d593 100644
--- a/piclib/prelude.scm
+++ b/piclib/prelude.scm
@@ -299,13 +299,6 @@
      (lambda (form r c)
        `(,(r 'let*-values) ,@(cdr form)))))
 
-  (define (vector-map proc vect)
-    (do ((i 0 (+ i 1))
-         (u (make-vector (vector-length vect))))
-        ((= i (vector-length vect))
-         u)
-      (vector-set! u i (proc (vector-ref vect i)))))
-
   (define (walk proc expr)
     (cond
      ((null? expr)
@@ -314,7 +307,7 @@
       (cons (proc (car expr))
             (walk proc (cdr expr))))
      ((vector? expr)
-      (vector-map proc expr))
+      (list->vector (map proc (vector->list expr))))
      (else
       (proc expr))))
 
diff --git a/src/cont.c b/src/cont.c
index de076874..11b5a3f6 100644
--- a/src/cont.c
+++ b/src/cont.c
@@ -210,6 +210,37 @@ walk_to_block(pic_state *pic, pic_block *here, pic_block *there)
   }
 }
 
+static pic_value
+pic_dynamic_wind(pic_state *pic, struct pic_proc *in, struct pic_proc *thunk, struct pic_proc *out)
+{
+  pic_block *here;
+  pic_value val;
+
+  if (in != NULL) {
+    pic_apply0(pic, in);        /* enter */
+  }
+
+  here = pic->blk;
+  pic->blk = (pic_block *)pic_alloc(pic, sizeof(pic_block));
+  pic->blk->prev = here;
+  pic->blk->depth = here->depth + 1;
+  pic->blk->in = in;
+  pic->blk->out = out;
+  pic->blk->refcnt = 1;
+  PIC_BLK_INCREF(pic, here);
+
+  val = pic_apply0(pic, thunk);
+
+  PIC_BLK_DECREF(pic, pic->blk);
+  pic->blk = here;
+
+  if (out != NULL) {
+    pic_apply0(pic, out);       /* exit */
+  }
+
+  return val;
+}
+
 noreturn static pic_value
 cont_call(pic_state *pic)
 {
@@ -286,33 +317,10 @@ static pic_value
 pic_cont_dynamic_wind(pic_state *pic)
 {
   struct pic_proc *in, *thunk, *out;
-  pic_value v;
 
   pic_get_args(pic, "lll", &in, &thunk, &out);
 
-  /* enter */
-  pic_apply0(pic, in);
-  {
-    pic_block *here;
-
-    here = pic->blk;
-    pic->blk = (pic_block *)pic_alloc(pic, sizeof(pic_block));
-    pic->blk->prev = here;
-    pic->blk->depth = here->depth + 1;
-    pic->blk->in = in;
-    pic->blk->out = out;
-    pic->blk->refcnt = 1;
-    PIC_BLK_INCREF(pic, here);
-
-    v = pic_apply0(pic, thunk);
-
-    PIC_BLK_DECREF(pic, pic->blk);
-    pic->blk = here;
-  }
-  /* exit */
-  pic_apply0(pic, out);
-
-  return v;
+  return pic_dynamic_wind(pic, in, thunk, out);
 }
 
 static pic_value