diff --git a/mes/module/mes/base.mes b/mes/module/mes/base.mes
index 790c7228..027a4344 100644
--- a/mes/module/mes/base.mes
+++ b/mes/module/mes/base.mes
@@ -119,12 +119,6 @@
 
 (define else #t)
 
-(define (procedure? p)
-  (cond ((builtin? p) #t)
-        ((and (pair? p) (eq? (car p) 'lambda)))
-        ((closure? p) #t)
-        (#t #f)))
-
 (define (map f h . t)
   (if (or (null? h)
           (and (pair? t) (null? (car t)))
diff --git a/mes/module/mes/type-0.mes b/mes/module/mes/type-0.mes
index b966ba58..beefbf06 100644
--- a/mes/module/mes/type-0.mes
+++ b/mes/module/mes/type-0.mes
@@ -76,6 +76,12 @@
 (define (port? x)
   (eq? (core:type x) <cell:port>))
 
+(define (procedure? p)
+  (and (or (builtin? p)
+           (and (pair? p) (eq? (car p) 'lambda))
+           (closure? p))
+       #t))
+
 (define (special? x)
   (eq? (core:type x) <cell:special>))