diff --git a/lib/srfi/srfi-0.scm b/lib/srfi/srfi-0.scm
new file mode 100644
index 00000000..8d279a0f
--- /dev/null
+++ b/lib/srfi/srfi-0.scm
@@ -0,0 +1,10 @@
+(define mes '(0 1))
+
+(define (cond-expand-expander clauses)
+  (let loop ((clauses clauses))
+    (if (defined? (caar clauses))
+        (eval (cons 'begin (cdar clauses)) (current-module))
+        (loop (cdr clauses)))))
+
+(define-macro (cond-expand . clauses)
+  `(cond-expand-expander (quote ,clauses)))
diff --git a/scm.mes b/scm.mes
index edfa8bdc..bf07eadf 100755
--- a/scm.mes
+++ b/scm.mes
@@ -98,8 +98,8 @@
 (define (apply f args)
   (eval (cons f args) (current-module)))
 
-(define (defined? x)
-  (assq x (current-module)))
+(define-macro (defined? x)
+  `(assq ,x (cddr (current-module))))
 
 (define (procedure? p)
   (cond ((builtin? p) #t)
@@ -199,8 +199,6 @@
         (set! counter (+ counter 1))
         (string->symbol (string-append "g" value))))))
 
-
-()
 ;; srfi-1
 (define (last-pair lst)
   (let loop ((lst lst))
diff --git a/test.mes b/test.mes
index 63b5e076..f4ab1a93 100644
--- a/test.mes
+++ b/test.mes
@@ -32,7 +32,8 @@
             ((car t) (display ": pass") (newline) (set! pass (+ pass 1)))
             (#t (display ": fail") (newline) (set! fail (+ fail 1)))))))
 
-(define (guile?) (defined? 'gc))
+;;(define (guile?) (defined? 'gc))
+(define (guile?) #f)
 (when (guile?)
   (module-define! (current-module) 'builtin? (lambda (. x) #t))
   (use-modules (srfi srfi-1)))
@@ -234,6 +235,8 @@
 ;;      (circular-list? x))
 ;;    #t))
 
+(pass-if "cond-expand" (sequal? (cond-expand (foobar #f) (mes (display ": pass: *YAY*") 'mes)) 'mes))
+
 (newline)
 (display "passed: ") (display (car (result))) (newline)
 (display "failed: ") (display (cadr (result))) (newline)