diff --git a/make/pkgs/mod/files/root/usr/bin/prepare-downgrade b/make/pkgs/mod/files/root/usr/bin/prepare-downgrade
index 1aa1bcaf7b..583ad2857c 100755
--- a/make/pkgs/mod/files/root/usr/bin/prepare-downgrade
+++ b/make/pkgs/mod/files/root/usr/bin/prepare-downgrade
@@ -8,7 +8,7 @@ if [ -e /var/tmp/version ]; then
 	echo 'already done.'
 else
 	MAJOR="$(/etc/version -v | sed 's/^[0-9]*\.//;s/\.[0-9]*$//')"
-	[ "$MAJOR" -gt 6 ] 2>/dev/null && FAKEVER="06.90" || FAKEVER="01.01"
+	[ "$MAJOR" -gt 6 ] 2>/dev/null && FAKEVER="0$(( $MAJOR - 1 )).90" || FAKEVER="01.01"
 	sed "s/\({CONFIG_VERSION_MAJOR}\)[^\"]*\(.*\)/\1.$FAKEVER\2/" /etc/version > /var/tmp/version
 	chmod +x /var/tmp/version
 	mount -o bind /var/tmp/version /etc/version