diff --git a/Functionals.Rmd b/Functionals.Rmd
index 7e7a017aa..e4d7f0ba2 100644
--- a/Functionals.Rmd
+++ b/Functionals.Rmd
@@ -1128,5 +1128,5 @@ str(optimise(sin, c(0, pi), maximum = TRUE))
 1.  What do `eapply()` and `rapply()` do? Does purrr have equivalents?
 
 1.  Challenge: read about the 
-    [fixed point algorithm](https://mitpress.mit.edu/sites/default/files/sicp/full-text/book/book-Z-H-12.html#%25_idx_1096).
+    [fixed point algorithm](https://web.archive.org/web/20220614001903/https://mitpress.mit.edu/sites/default/files/sicp/full-text/book/book-Z-H-12.html).
     Complete the exercises using R.