diff --git a/man7/ip.7 b/man7/ip.7
index aa57247f8..9f6860662 100644
--- a/man7/ip.7
+++ b/man7/ip.7
@@ -206,6 +206,7 @@ A boolean integer flag is zero when it is false, otherwise true.
 .\" FIXME Document IP_FREEBIND
 .\" Boolean
 .\" Since Linux 2.4.0-test10
+.\" https://bugzilla.kernel.org/show_bug.cgi?id=20082
 .\"
 .TP
 .BR IP_ADD_MEMBERSHIP " (since Linux 1.2)"