diff --git a/share/man/man5/periodic.conf.5 b/share/man/man5/periodic.conf.5
--- a/share/man/man5/periodic.conf.5
+++ b/share/man/man5/periodic.conf.5
@@ -645,7 +645,8 @@
 .Xr diff 1
 utility when generating differences.
 The default is
-.Fl b u .
+.Fl b
+.Fl U Cm 0 .
 .El
 .Pp
 The following variables are used by the standard scripts that reside in
@@ -814,7 +815,8 @@
 .Xr diff 1
 utility when generating differences.
 The default is
-.Fl b u .
+.Fl b
+.Fl U Cm 0 .
 .It Va security_status_chksetuid_enable
 .Pq Vt bool
 Set to
diff --git a/usr.sbin/periodic/periodic.conf b/usr.sbin/periodic/periodic.conf
--- a/usr.sbin/periodic/periodic.conf
+++ b/usr.sbin/periodic/periodic.conf
@@ -31,7 +31,7 @@
 # that output.  $daily_output might be set to /var/log/daily.log if you
 # wish to log the daily output and have the files rotated by newsyslog(8)
 #
-daily_diff_flags="-u"				# flags for diff output
+daily_diff_flags="-b -U 0"				# flags for diff output
 daily_output="root"					# user or /file
 daily_show_success="YES"				# scripts returning 0
 daily_show_info="YES"					# scripts returning 1
@@ -249,7 +249,7 @@
 # These options are used by the security periodic(8) scripts spawned in
 # daily and weekly 450.status-security.
 security_status_logdir="/var/log"			# Directory for logs
-security_status_diff_flags="-b -u"			# flags for diff output
+security_status_diff_flags="-b -U 0"			# flags for diff output
 
 # Each of the security_status_*_period options below can have one of the
 # following values: