diff --git a/README.md b/README.md
index 19b6b78..1e52dea 100644
--- a/README.md
+++ b/README.md
@@ -7,5 +7,6 @@ These are not capable of being compiled today with modern c compilers like gcc.
 
 You guys might be able to play around building this compilier with Aiju's pdp-11/unix emulator. I havent tried building this myself so I cant confirm it works, but I posted the link to his emulator for anybody wanting to hack around with it.
 
-Source: [https://www.bell-labs.com/usr/dmr/www/primevalC.html]
+Source: [https://www.bell-labs.com/usr/dmr/www/primevalC.html] [alt http://cm.bell-labs.co/who/dmr/primevalC.html]
+
 PDP-11 Emulator[http://pdp11.aiju.de/]