diff --git a/plugins/network/upnpc_ b/plugins/network/upnpc_
index c50037c6..c29022e8 100755
--- a/plugins/network/upnpc_
+++ b/plugins/network/upnpc_
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/sh -u
 # -*- sh -*-
 
 : << =cut
@@ -16,7 +16,7 @@ router using UPnP. It can monitor the following aspects, and plot them as separa
 
 =head1 APPLICABLE SYSTEMS
 
-Linux systems with upnpc installed.
+Linux systems with upnpc installed (miniupnpc package).
 
 =head1 CONFIGURATION
 
@@ -24,11 +24,13 @@ None needed.
 
 =head1 AUTHOR
 
-Olivier Mehani <shtrom+munin@ssji.net>
+Olivier Mehani
+
+Copyright (C) 2016,2019 Olivier Mehani <shtrom+munin@ssji.net>
 
 =head1 LICENSE
 
-SPDX-License-Identifier: GPL-2.0-or-later
+SPDX-License-Identifier: GPL-3.0-or-later
 
 =head1 MAGIC MARKERS
 
@@ -37,21 +39,38 @@ SPDX-License-Identifier: GPL-2.0-or-later
 
 =cut
 
+if [ "${MUNIN_DEBUG:-0}" = 1 ]; then
+    set -x
+fi
+
+if ! command -v upnpc >/dev/null; then
+	echo "upnpc not found (miniupnpc package)" >&2
+	exit 1
+fi
+
+PLUGIN_NAME="$(basename "${0}")"
+MODE="$(echo "${PLUGIN_NAME}" | sed 's/.*_//')"
+DATA="$(upnpc -s)"
+SUPPORTED_MODES=$(
+	echo "${DATA}" | sed -n " \
+		s/.*Bytes.*/traffic/p; \
+		s/.*MaxBitRate.*/bitrate/p; \
+		s/.*Packets.*/pkts/p; \
+		s/.*uptime=.*/uptime/p; \
+	")
+
 autoconf() {
-	which upnpc >/dev/null && upnpc -s >/dev/null 2>&1 && echo yes || echo "no (No upnpc or no UPnP router)"
+	test -n "${DATA}" && echo yes || echo "no (No UPnP router detected)"
 }
 
 suggest () {
-	upnpc -s | sed -n " \
-		s/.*uptime=.*/uptime/p; \
-		s/.*MaxBitRate.*/bitrate/p; \
-		s/.*Bytes.*/traffic/p; \
-		s/.*Packets.*/pkts/p; \
-			"
+	for mode in ${SUPPORTED_MODES}; do
+		echo "${mode}"
+	done
 }
 
 config () {
-	case $1 in
+	case ${1} in
 		"uptime")
 			cat << EOF
 graph_title Uplink connection uptime
@@ -71,11 +90,7 @@ graph_args --base 1000 -l 0
 graph_category network
 graph_vlabel bitrate down (-) / up (+)
 down.label bps
-down.warning 4194304:
-down.critical 1048576:
 up.label bps
-up.warning 524288:
-up.critical 131072:
 down.graph no
 up.negative down
 EOF
@@ -114,35 +129,35 @@ down.graph no
 up.negative down
 EOF
 			;;
-		"*")
-			echo "$0: unknown mode '$1'" >&2
+		*)
+			echo "unknown mode '${1}'" >&2
 			exit 1
+			;;
 	esac
 }
 
 fetch () {
-	case $1 in
+	case "${1}" in
 		"uptime")
-		upnpc -s | sed -n "s/.*uptime=\([0-9]\+\)s.*/uptime.value \1/p"
+		echo "${DATA}" | sed -n "s/.*uptime=\([0-9]\+\)s.*/uptime.value \1/p"
 			;;
 		"bitrate")
-		upnpc -s | sed -n "s/^MaxBitRateDown : \([0-9]\+\) bps.*MaxBitRateUp \([0-9]\+\) bps.*/down.value \1\nup.value \2/p"
+		echo "${DATA}" | sed -n "s/^MaxBitRateDown : \([0-9]\+\) bps.*MaxBitRateUp \([0-9]\+\) bps.*/down.value \1\nup.value \2/p"
 			;;
 		"traffic")
-		upnpc -s | sed -n "s/^Bytes:\s*Sent:\s*\([0-9]\+\).*Recv:\s*\([0-9]\+\).*/up.value \1\ndown.value \2/p"
+		echo ${DATA} | sed -n "s/^Bytes:\s*Sent:\s*\([0-9]\+\).*Recv:\s*\([0-9]\+\).*/up.value \1\ndown.value \2/p"
 			;;
 		"pkts")
-		upnpc -s | sed -n "s/^Packets:\s*Sent:\s*\([0-9]\+\).*Recv:\s*\([0-9]\+\).*/up.value \1\ndown.value \2/p"
+		echo "${DATA}" | sed -n "s/^Packets:\s*Sent:\s*\([0-9]\+\).*Recv:\s*\([0-9]\+\).*/up.value \1\ndown.value \2/p"
 			;;
-		"*")
-			echo "$0: unknown mode '$1'" >&2
+		*)
+			echo "unknown mode '${1}'" >&2
 			exit 1
+			;;
 	esac
 }
 
-mode=`echo $0 | sed 's/.*_//'`
-
-case $1 in
+case ${1:-} in
 	"autoconf")
 		autoconf
 		;;
@@ -150,9 +165,9 @@ case $1 in
 		suggest
 		;;
 	"config")
-		config $mode
+		config "${MODE}"
 		;;
 	*)
-		fetch $mode
+		fetch "${MODE}"
 		;;
 esac