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
@@ -815,7 +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/etc/daily/200.backup-passwd b/usr.sbin/periodic/etc/daily/200.backup-passwd
--- a/usr.sbin/periodic/etc/daily/200.backup-passwd
+++ b/usr.sbin/periodic/etc/daily/200.backup-passwd
@@ -40,7 +40,7 @@
 	    then
 		[ $rc -lt 1 ] && rc=1
 		echo "$host passwd diffs:"
-		diff -uI '^#' $bak/master.passwd.bak /etc/master.passwd |\
+		diff ${daily_diff_flags} -I '^#' $bak/master.passwd.bak /etc/master.passwd |\
 			sed 's/^\([-+ ][^:]*\):[^:]*:/\1:(password):/'
 		mv $bak/master.passwd.bak $bak/master.passwd.bak2
 		cp -p /etc/master.passwd $bak/master.passwd.bak || rc=3
@@ -57,7 +57,7 @@
 	    then
 		[ $rc -lt 1 ] && rc=1
 		echo "$host group diffs:"
-		diff -u $bak/group.bak /etc/group
+		diff ${daily_diff_flags} $bak/group.bak /etc/group
 		mv $bak/group.bak $bak/group.bak2
 		cp -p /etc/group $bak/group.bak || rc=3
 	    fi
diff --git a/usr.sbin/periodic/etc/daily/210.backup-aliases b/usr.sbin/periodic/etc/daily/210.backup-aliases
--- a/usr.sbin/periodic/etc/daily/210.backup-aliases
+++ b/usr.sbin/periodic/etc/daily/210.backup-aliases
@@ -34,7 +34,7 @@
 	    then
 		[ $rc -lt 1 ] && rc=1
 		echo "$host aliases diffs:"
-		diff -u $bak/aliases.bak /etc/mail/aliases
+		diff ${daily_diff_flags} $bak/aliases.bak /etc/mail/aliases
 		mv $bak/aliases.bak $bak/aliases.bak2
 		cp -p /etc/mail/aliases $bak/aliases.bak || rc=3
 	    fi
diff --git a/usr.sbin/periodic/etc/daily/221.backup-gpart b/usr.sbin/periodic/etc/daily/221.backup-gpart
--- a/usr.sbin/periodic/etc/daily/221.backup-gpart
+++ b/usr.sbin/periodic/etc/daily/221.backup-gpart
@@ -27,7 +27,7 @@
 			rm "${file}.tmp"
 		else
 			rc=1
-			[ -n "$show_diff" ] && diff "${file}.bak" "${file}.tmp"
+			[ -n "$show_diff" ] && diff ${daily_diff_flags} "${file}.bak" "${file}.tmp"
 			mv "${file}.bak" "${file}.bak2" || rc=3
 			mv "${file}.tmp" "${file}.bak" || rc=3
 		fi
diff --git a/usr.sbin/periodic/etc/daily/222.backup-gmirror b/usr.sbin/periodic/etc/daily/222.backup-gmirror
--- a/usr.sbin/periodic/etc/daily/222.backup-gmirror
+++ b/usr.sbin/periodic/etc/daily/222.backup-gmirror
@@ -25,7 +25,7 @@
 			rm "${file}.tmp"
 		else
 			rc=1
-			[ -n "$show_diff" ] && diff "${file}.bak" "${file}.tmp"
+			[ -n "$show_diff" ] && diff ${daily_diff_flags} "${file}.bak" "${file}.tmp"
 			mv "${file}.bak" "${file}.bak2" || rc=3
 			mv "${file}.tmp" "${file}.bak" || rc=3
 		fi
diff --git a/usr.sbin/periodic/etc/daily/223.backup-zfs b/usr.sbin/periodic/etc/daily/223.backup-zfs
--- a/usr.sbin/periodic/etc/daily/223.backup-zfs
+++ b/usr.sbin/periodic/etc/daily/223.backup-zfs
@@ -25,7 +25,7 @@
 			rm "${file}.tmp"
 		else
 			rc=1
-			[ -n "$show_diff" ] && diff "${file}.bak" "${file}.tmp"
+			[ -n "$show_diff" ] && diff ${daily_diff_flags} "${file}.bak" "${file}.tmp"
 			mv "${file}.bak" "${file}.bak2" || rc=3
 			mv "${file}.tmp" "${file}.bak" || rc=3
 		fi
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
@@ -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: