diff --git a/man2/pidfd_open.2 b/man2/pidfd_open.2
index 98fe449b1..51136e170 100644
--- a/man2/pidfd_open.2
+++ b/man2/pidfd_open.2
@@ -88,6 +88,19 @@ the file descriptor indicates as readable.
 Note, however, that in the current implementation,
 nothing can be read from the file descriptor.
 .PP
+The
+.BR pidfd_open ()
+system call is the preferred way of obtaining a PID file descriptor.
+The alternative is to obtain a file descriptor by opening a
+.I /proc/[pid]
+directory.
+However, the latter technique is possible only if the
+.BR proc (5)
+file system is mounted;
+furthermore, the file descriptor obtained in this way is
+.I not
+pollable.
+.PP
 See also the discussion of the
 .BR CLONE_PIDFD
 flag in