diff --git a/piclib/picrin/macro.scm b/piclib/picrin/macro.scm
index b2cccec3..9c3d482e 100644
--- a/piclib/picrin/macro.scm
+++ b/piclib/picrin/macro.scm
@@ -24,9 +24,6 @@
                 (go (+ i 1)))))
     (go 0))
 
-  (define (vector-map proc expr)
-    (list->vector (map proc (vector->list expr))))
-
   (define (walk proc expr)
     "walk on symbols"
     (if (null? expr)