diff --git a/Protocol.md b/Protocol.md
index 890ee3e..12f9c0a 100644
--- a/Protocol.md
+++ b/Protocol.md
@@ -3,7 +3,7 @@
 * The messages uses [ActivityStreams](http://activitystrea.ms/head/activity-schema.html).
 * [Webfinger](https://code.google.com/p/webfinger/wiki/WebFingerProtocol) is used for the discovery of users
 * [Salmon](https://en.wikipedia.org/wiki/Salmon_%28protocol%29) is used as a message exchange protocol for replies and mentions.
-* [Portable Contacts](http://portablecontacts.net/draft-spec.html) is used for friends lists.
+* [Portable Contacts](https://web.archive.org/web/20160426223008/http://portablecontacts.net/draft-spec.html) is used for friends lists.
 * [pubsubhubbub](https://code.google.com/p/pubsubhubbub/) is used for OStatus.
 
 # Resources