diff --git a/man7/unix.7 b/man7/unix.7
index 38e00c6c8..efa85c7d8 100644
--- a/man7/unix.7
+++ b/man7/unix.7
@@ -285,6 +285,19 @@ ancillary message.
 When this option is set and the socket is not yet connected
 a unique name in the abstract namespace will be generated automatically.
 Expects an integer boolean flag.
+.TP
+.B SO_PASSSEC
+Enables receiving of the SELinux security label of the sending
+process in an ancillary message of type
+.BR SCM_SECURITY .
+Expects an integer boolean flag.
+Supported for UNIX domain datagram sockets
+.\" commit 877ce7c1b3afd69a9b1caeb1b9964c992641f52a
+since Linux 2.6.18;
+support for UNIX domain stream sockets was added
+.\" commit 37a9a8df8ce9de6ea73349c9ac8bdf6ba4ec4f70
+in Linux 4.2.
+.\"
 .SS Autobind feature
 If a
 .BR bind (2)