- deb http://ftp.debian.org/debian/ jessie-backports main contrib non-free
- deb-src http://ftp.debian.org/debian/ jessie-backports main contrib non-free
+ deb http://ftp.debian.org/debian/ stretch-backports main contrib non-free
+ deb-src http://ftp.debian.org/debian/ stretch-backports main contrib non-free