diff --git a/site/how-it-works.md b/site/how-it-works.md
index 27723f52..835ac533 100644
--- a/site/how-it-works.md
+++ b/site/how-it-works.md
@@ -95,7 +95,7 @@ the MAC. This way weave peers never need to exchange the MAC addresses
 of clients and need not take any special action for ARP traffic and
 MAC discovery.
 
-### Crypto
+### <a name="crypto"></a>Crypto
 
 Weave can be configured to encrypt both the data passing over the TCP
 connections and the payloads of UDP packets sent between peers. This