diff --git a/piclib/prelude.scm b/piclib/prelude.scm
index 114bcffa..af357cdb 100644
--- a/piclib/prelude.scm
+++ b/piclib/prelude.scm
@@ -667,16 +667,6 @@
       res))
   (fold vector-append-2-inv #() vs))
 
-(define (vector-fill! v fill . opts)
-  (let ((start (if (pair? opts) (car opts) 0))
-	(end (if (>= (length opts) 2)
-		 (cadr opts)
-		 (vector-length v))))
-    (do ((i start (+ i 1)))
-	((= i end)
-	 #f)
-      (vector-set! v i fill))))
-
 (define (vector->string . args)
   (list->string (apply vector->list args)))
 
diff --git a/src/vector.c b/src/vector.c
index af9264d1..8fe9392c 100644
--- a/src/vector.c
+++ b/src/vector.c
@@ -173,6 +173,29 @@ pic_vec_vector_copy(pic_state *pic)
   return pic_obj_value(to);
 }
 
+static pic_value
+pic_vec_vector_fill_i(pic_state *pic)
+{
+  pic_vec *vec;
+  pic_value obj;
+  int n, start, end;
+
+  n = pic_get_args(pic, "vo|ii", &vec, &obj, &start, &end);
+
+  switch (n) {
+  case 2:
+    start = 0;
+  case 3:
+    end = vec->len;
+  }
+
+  while (start < end) {
+    vec->data[start++] = obj;
+  }
+
+  return pic_none_value();
+}
+
 static pic_value
 pic_vec_list_to_vector(pic_state *pic)
 {
@@ -225,6 +248,7 @@ pic_init_vector(pic_state *pic)
   pic_defun(pic, "vector-set!", pic_vec_vector_set);
   pic_defun(pic, "vector-copy!", pic_vec_vector_copy_i);
   pic_defun(pic, "vector-copy", pic_vec_vector_copy);
+  pic_defun(pic, "vector-fill!", pic_vec_vector_fill_i);
   pic_defun(pic, "list->vector", pic_vec_list_to_vector);
   pic_defun(pic, "vector->list", pic_vec_vector_to_list);
 }