diff --git a/book/Middleware.markdown b/book/Middleware.markdown
index da71159..1675cf5 100755
--- a/book/Middleware.markdown
+++ b/book/Middleware.markdown
@@ -38,6 +38,6 @@ debugging, URL routing, authentication, and session handling. Sinatra uses many
 of of these components automatically based on configuration so you typically
 don’t have to use them explicitly.
 
-[rack]: http://rack.rubyforge.org/
+[rack]: https://github.com/rack/rack
 [rack_builder]: https://rubydoc.info/github/rack/rack/Rack/Builder