diff --git a/package/base-files/files/sbin/sysupgrade b/package/base-files/files/sbin/sysupgrade
index 935d08048e..3a5087a0c8 100755
--- a/package/base-files/files/sbin/sysupgrade
+++ b/package/base-files/files/sbin/sysupgrade
@@ -2,10 +2,8 @@
 
 . /lib/functions.sh
 . /lib/functions/system.sh
-. /usr/share/libubox/jshn.sh
 
 # initialize defaults
-export MTD_ARGS=""
 export MTD_CONFIG_ARGS=""
 export INTERACTIVE=0
 export VERBOSE=1
@@ -192,6 +190,9 @@ add_overlayfiles() {
 	return 0
 }
 
+# hooks
+sysupgrade_image_check="fwtool_check_signature fwtool_check_image platform_check_image"
+
 if [ $SAVE_OVERLAY = 1 ]; then
 	[ ! -d /overlay/upper/etc ] && {
 		echo "Cannot find '/overlay/upper/etc', required for '-c'" >&2
@@ -248,7 +249,7 @@ do_save_conffiles() {
 
 	v "Saving config files..."
 	[ "$VERBOSE" -gt 1 ] && TAR_V="v" || TAR_V=""
-	tar c${TAR_V}zf "$conf_tar" -T "$CONFFILES" 2>/dev/null
+	tar c${TAR_V}zpf "$conf_tar" -T "$CONFFILES" 2>/dev/null
 	if [ "$?" -ne 0 ]; then
 		echo "Failed to create the configuration backup."
 		rm -f "$conf_tar"
@@ -314,19 +315,20 @@ case "$IMAGE" in
 		;;
 esac
 
-json_load "$(/usr/libexec/validate_firmware_image "$IMAGE")" || {
-	echo "Failed to check image"
-	exit 1
-}
-json_get_var valid "valid"
-[ "$valid" -eq 0 ] && {
-	if [ $FORCE -eq 1 ]; then
-		echo "Image check failed but --force given - will update anyway!" >&2
-	else
-		echo "Image check failed." >&2
-		exit 1
-	fi
-}
+export ARGV="$IMAGE"
+export ARGC=1
+
+for check in $sysupgrade_image_check; do
+	( $check "$IMAGE" ) || {
+		if [ $FORCE -eq 1 ]; then
+			echo "Image check '$check' failed but --force given - will update anyway!" >&2
+			break
+		else
+			echo "Image check '$check' failed." >&2
+			exit 1
+		fi
+	}
+done
 
 if [ -n "$CONF_IMAGE" ]; then
 	case "$(get_magic_word $CONF_IMAGE cat)" in
@@ -351,27 +353,24 @@ if [ $TEST -eq 1 ]; then
 	exit 0
 fi
 
+if [ $SAVE_PARTITIONS -eq 0 ]; then
+	touch /tmp/sysupgrade.always.overwrite.bootdisk.partmap
+else
+	rm -f /tmp/sysupgrade.always.overwrite.bootdisk.partmap
+fi
+
 install_bin /sbin/upgraded
 v "Commencing upgrade. Closing all shell sessions."
 
-COMMAND='/lib/upgrade/do_stage2'
+COMMAND='. /lib/functions.sh; include /lib/upgrade; do_upgrade_stage2'
 
 if [ -n "$FAILSAFE" ]; then
 	printf '%s\x00%s\x00%s' "$RAM_ROOT" "$IMAGE" "$COMMAND" >/tmp/sysupgrade
 	lock -u /tmp/.failsafe
 else
-	force_attr=""
-	[ $FORCE -eq 1 ] && force_attr="\"force\": true,"
-	backup_attr=""
-	[ $SAVE_CONFIG -eq 1 ] && backup_attr="\"backup\": $(json_string $CONF_TAR),"
 	ubus call system sysupgrade "{
 		\"prefix\": $(json_string "$RAM_ROOT"),
 		\"path\": $(json_string "$IMAGE"),
-		$force_attr
-		$backup_attr
-		\"command\": $(json_string "$COMMAND"),
-		\"options\": {
-			\"save_partitions\": $SAVE_PARTITIONS
-		}
+		\"command\": $(json_string "$COMMAND")
 	}"
 fi