diff --git a/usr.sbin/bsdinstall/bsdinstall b/usr.sbin/bsdinstall/bsdinstall
--- a/usr.sbin/bsdinstall/bsdinstall
+++ b/usr.sbin/bsdinstall/bsdinstall
@@ -34,6 +34,21 @@
 export DEBUG_SELF_INITIALIZE=
 export DEBUG_INITIALIZE_FILE=
 
+# When common.subr is included, it automatically scans "$@" for `-d' and/or
+# `-D file' arguments to conditionally enable debugging. Similarly, when
+# dialog.subr is included, it automatically scans "$@" for `-X' and/or `-S'.
+# To prevent this scanning from becoming confused by extra options, define
+# any/all extra arguments to use in the optstring to getopts when scanning
+# for dedicated options such as those described.
+#
+# NOTE: This needs to be declared before including `common.subr'.
+# NOTE: You really only need to list flags that require an argument as unknown
+#       flags are silently accepted unless they take an argument (in which case
+#       the following argument will terminate option processing unless it looks
+#       like a flag).
+#
+GETOPTS_EXTRA=
+
 BSDCFG_SHARE="/usr/share/bsdconfig"
 . $BSDCFG_SHARE/common.subr || exit 1
 
@@ -49,13 +64,28 @@
 
 export debugFile="${debugFile-${BSDINSTALL_LOG-${TMPDIR}/bsdinstall_log}}"
 
+############################################################ USAGE
+
+usage()
+{
+	echo "Usage: bsdinstall [-$GETOPTS_EXTRA$GETOPTS_STDARGS][target][...]" 1>&2
+	echo "  -d	Enable debugging output" 1>&2
+	echo "  -D	Save debugging output to a file" 1>&2
+	return 1
+}
+
 ############################################################ MAIN
 
 #
 # Process command-line arguments
 #
-while getopts $GETOPTS_STDARGS ignored; do
-	: just skipping known flags
+while getopts "$GETOPTS_EXTRA$GETOPTS_STDARGS" name; do
+	case "$name" in
+		'?')
+			usage
+			exit $?
+			;;
+	esac
 done
 shift $(( $OPTIND - 1 ))
 
diff --git a/usr.sbin/bsdinstall/scripts/jail b/usr.sbin/bsdinstall/scripts/jail
--- a/usr.sbin/bsdinstall/scripts/jail
+++ b/usr.sbin/bsdinstall/scripts/jail
@@ -54,6 +54,14 @@
 	fi
 }
 
+#
+# Process command-line arguments
+#
+while getopts $GETOPTS_STDARGS$GETOPTS_EXTRA$GETOPTS_ALLFLAGS flag; do
+	:
+done
+shift $(( $OPTIND - 1 ))
+
 if [ -z "$1" ]; then
 	error "Directory can not be empty\n\nUsage:\nbsdinstall jail directory"
 fi
diff --git a/usr.sbin/bsdinstall/scripts/netconfig b/usr.sbin/bsdinstall/scripts/netconfig
--- a/usr.sbin/bsdinstall/scripts/netconfig
+++ b/usr.sbin/bsdinstall/scripts/netconfig
@@ -44,6 +44,14 @@
 : ${BSDDIALOG_ERROR=255}
 : ${DIALOG="bsddialog"}
 
+#
+# Process command-line arguments
+#
+while getopts $GETOPTS_STDARGS$GETOPTS_EXTRA$GETOPTS_ALLFLAGS flag; do
+	:
+done
+shift $(( $OPTIND - 1 ))
+
 for IF in `ifconfig -l`; do
 	test "$IF" = "lo0" && continue
 	(ifconfig -g wlan | egrep -wq $IF) && continue
diff --git a/usr.sbin/bsdinstall/scripts/netconfig_ipv4 b/usr.sbin/bsdinstall/scripts/netconfig_ipv4
--- a/usr.sbin/bsdinstall/scripts/netconfig_ipv4
+++ b/usr.sbin/bsdinstall/scripts/netconfig_ipv4
@@ -38,6 +38,14 @@
 : ${BSDDIALOG_OK=0}
 : ${BSDDIALOG_CANCEL=1}
 
+#
+# Process command-line arguments
+#
+while getopts $GETOPTS_STDARGS$GETOPTS_EXTRA$GETOPTS_ALLFLAGS flag; do
+	:
+done
+shift $(( $OPTIND - 1 ))
+
 INTERFACE=$1
 IFCONFIG_PREFIX="$2"
 AUTO="${3:-}"
diff --git a/usr.sbin/bsdinstall/scripts/netconfig_ipv6 b/usr.sbin/bsdinstall/scripts/netconfig_ipv6
--- a/usr.sbin/bsdinstall/scripts/netconfig_ipv6
+++ b/usr.sbin/bsdinstall/scripts/netconfig_ipv6
@@ -47,6 +47,14 @@
 # - Add DHCPv6 support once FreeBSD ships with it.
 #
 
+#
+# Process command-line arguments
+#
+while getopts $GETOPTS_STDARGS$GETOPTS_EXTRA$GETOPTS_ALLFLAGS flag; do
+	:
+done
+shift $(( $OPTIND - 1 ))
+
 INTERFACE=$1
 AUTO="${2:-}"
 case "${INTERFACE}" in
diff --git a/usr.sbin/bsdinstall/scripts/script b/usr.sbin/bsdinstall/scripts/script
--- a/usr.sbin/bsdinstall/scripts/script
+++ b/usr.sbin/bsdinstall/scripts/script
@@ -82,6 +82,14 @@
 set -e
 trap error EXIT
 
+#
+# Process command-line arguments
+#
+while getopts $GETOPTS_STDARGS$GETOPTS_EXTRA$GETOPTS_ALLFLAGS flag; do
+	:
+done
+shift $(( $OPTIND - 1 ))
+
 SCRIPT="$1"
 shift
 
diff --git a/usr.sbin/bsdinstall/scripts/wlanconfig b/usr.sbin/bsdinstall/scripts/wlanconfig
--- a/usr.sbin/bsdinstall/scripts/wlanconfig
+++ b/usr.sbin/bsdinstall/scripts/wlanconfig
@@ -148,6 +148,14 @@
 
 ############################################################ MAIN
 
+#
+# Process command-line arguments
+#
+while getopts $GETOPTS_STDARGS$GETOPTS_EXTRA$GETOPTS_ALLFLAGS flag; do
+	:
+done
+shift $(( $OPTIND - 1 ))
+
 : > "$BSDINSTALL_TMPETC/wpa_supplicant.conf"
 chmod 0600 "$BSDINSTALL_TMPETC/wpa_supplicant.conf"