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
@@ -23,7 +23,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd March 9, 2022
+.Dd December 8, 2023
 .Dt PERIODIC.CONF 5
 .Os
 .Sh NAME
@@ -639,6 +639,14 @@
 Set to a list of extra scripts that should be run after all other
 daily scripts.
 All scripts must be absolute path names.
+.It Va daily_diff_flags
+.Pq Vt str
+Set to the arguments to pass to the
+.Xr diff 1
+utility when generating differences.
+The default is
+.Fl b
+.Fl U Cm 0 .
 .El
 .Pp
 The following variables are used by the standard scripts that reside in
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
@@ -31,6 +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="-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