diff --git a/scheme/base.sld b/scheme/base.sld
index f9355155..50fa8cc8 100644
--- a/scheme/base.sld
+++ b/scheme/base.sld
@@ -1864,16 +1864,12 @@
   (lambda (obj val)
     (vector-set! (vector-ref obj 2) idx val)))
 
-;; Find index of element in list, or -1 if not found
+;; Find index of element in list, or #f if not found
 (define _list-index
-  (lambda (e lst)
-    (if (null? lst)
-      -1
-      (if (eq? (car lst) e)
-        0
-        (if (= (_list-index e (cdr lst)) -1) 
-          -1
-          (+ 1 (_list-index e (cdr lst))))))))
+  (lambda (e lst1)
+    (let lp ((lis lst1) (n 0))
+      (and (not (null? lis))
+           (if (eq? e (car lis)) n (lp (cdr lis) (+ n 1)))))))
 
 (define (record? obj)
   (and (vector? obj)