diff --git a/man7/unix.7 b/man7/unix.7
index 4d22661e1..e21172b7d 100644
--- a/man7/unix.7
+++ b/man7/unix.7
@@ -165,6 +165,14 @@ The
 .B MSG_MORE
 flag is not supported by Unix domain sockets.
 
+The use of
+.B MSG_TRUNC
+in the
+.I flags
+argument of
+.BR recv (2)
+is not supported by Unix domain sockets.
+
 The
 .B SO_SNDBUF
 socket option does have an effect for Unix domain sockets, but the