diff --git a/pimd/TODO b/pimd/TODO
index 80835e4..2308573 100644
--- a/pimd/TODO
+++ b/pimd/TODO
@@ -264,6 +264,7 @@
 T31 If an interface changes one of its secondary IP addresses, a Hello
     message with an updated Address_List option and a non-zero
     HoldTime should be sent immediately.
+    See also detect_secondary_address_change
     See also CAVEAT C15.
     See also RFC 4601: 4.3.1.  Sending Hello Messages