diff --git a/tools/chibi-ffi b/tools/chibi-ffi
index 55081c12..bc728ac2 100755
--- a/tools/chibi-ffi
+++ b/tools/chibi-ffi
@@ -326,9 +326,10 @@
          (inline (and (> (length func) 3)
                       (cond ((assq 'inline (cdr (cddr func))) => cadr)
                             (else #f))))
-         (assert (and (> (length func) 3)
-                      (cond ((assq 'assert (cdr (cddr func))) => cdr)
-                            (else '())))))
+         (assert (or (and (> (length func) 3)
+                          (cond ((assq 'assert (cdr (cddr func))) => cdr)
+                                (else #f)))
+                     '())))
     (let lp ((ls (if (equal? (car (cddr func)) '(void)) '() (car (cddr func))))
              (i 0)
              (results '())