diff --git a/contrib/20.r7rs/scheme/lazy.scm b/contrib/20.r7rs/scheme/lazy.scm
index f429dcd0..d934ad45 100644
--- a/contrib/20.r7rs/scheme/lazy.scm
+++ b/contrib/20.r7rs/scheme/lazy.scm
@@ -30,7 +30,11 @@
     (let ((v (promise-value p)))
       (case (promise-state p)
         ((cached)  v)
-        ((chained) (force v))
+        ((chained) (let ()
+                     (when (eq? 'cached (promise-state v))
+                       (set-promise-state! p 'cached)
+                       (set-promise-value! p (promise-value v)))
+                     (force v)))
         ((pending) (let ((q (v)))
                      (when (eq? 'pending (promise-state p))
                        (set-promise-state! p 'chained)