diff --git a/timemaster.8 b/timemaster.8
index 9a3ddb4..062322b 100644
--- a/timemaster.8
+++ b/timemaster.8
@@ -250,10 +250,12 @@ for PTP sources (\fBntp_poll\fR) to specify a subsecond interval.
 The \fBntpd\fR limitations are:
 
 .RS
-Only the first two shared-memory segments created by the SHM refclock driver
-in \fBntpd\fR have owner-only access. Other segments are created with world
-access, possibly allowing any user on the system writing to the segments and
-disrupting the synchronization.
+In versions before 4.2.8p1, only the first two shared-memory segments created by
+the \fBntpd\fR SHM refclock driver have owner-only access. Other segments
+are created with world access, which allows any user on the system to write to
+the segments and disrupt or take control over the synchronization of the clock.
+In 4.2.8p1 the access was made configurable with the mode option, which is set
+by \fBtimemaster\fR for owner-ownly access.
 
 The shortest polling interval for all sources is 3 (8 seconds).
 
diff --git a/timemaster.c b/timemaster.c
index 83a5b83..eec0d0d 100644
--- a/timemaster.c
+++ b/timemaster.c
@@ -623,7 +623,8 @@ static void add_shm_source(int shm_segment, int poll, int dpoll, double delay,
 		break;
 	case NTPD:
 		string_appendf(ntp_config,
-			       "server 127.127.28.%d minpoll %d maxpoll %d\n"
+			       "server 127.127.28.%d minpoll %d maxpoll %d "
+			       "mode 1\n"
 			       "fudge 127.127.28.%d refid %s\n",
 			       shm_segment, poll, poll, shm_segment, refid);
 		break;