-# location based redirector gets it wrong with company VPN; also add deb-src
-sed -i "s/deb.debian.org/ftp.de.debian.org/; /^deb\b/ { p; s/^deb/deb-src/ }" /etc/apt/sources.list
+# otherwise installing systemd fails
+umount /var/log/journal
+
+# enable sources
+if [ -e /etc/apt/sources.list.d/debian.sources ]; then
+ sed -i "/^Types:/ s/deb$/deb deb-src/" /etc/apt/sources.list.d/debian.sources
+fi