diff --git a/TODO b/TODO
index ec64c552..e9e9954f 100644
--- a/TODO
+++ b/TODO
@@ -32,6 +32,7 @@ v vector-length
 v vector-ref
 v vector-set!
 v vector? 
-... possibly also: any, each, unquote-splicing, ...
-** implement extras: (gensym)
+v procedure?
+** any, each, unquote-splicing, ...
+** implement extras: v (gensym)
 ** hook-up sc-expand, see guile-1.0?: scheme:eval-transformer
diff --git a/scm.mes b/scm.mes
index 73f28a8b..c8768ecd 100755
--- a/scm.mes
+++ b/scm.mes
@@ -24,6 +24,11 @@
 (define (defined? x)
   (assq x (current-module)))
 
+(define (procedure? p)
+  (cond ((builtin? p) #t)
+        ((pair? p) (eq? (car p) 'lambda))
+        (#t #f)))
+
 (define (list . rest) rest)
 (define (vector . rest) (list->vector rest))
 (define assv assq)
diff --git a/test.mes b/test.mes
index 5d004d64..476fbe86 100644
--- a/test.mes
+++ b/test.mes
@@ -260,4 +260,12 @@
        (display ((lambda (x) x) (values 1 2 3)))
        (newline)))
 
+(display "(procedure? builtin?: ")
+(display (procedure? builtin?))
+(newline)
+
+(display "(procedure? procedure?): ")
+(display (procedure? procedure?))
+(newline)
+
 '()