Follow-up to: https://lists.debian.org/debian-ada/2014/03/msg00063.html. The bootstrap between gnat and gnat-4.6 in unstable gnat-4.6 4.6.4-2 (Source) Build-Depends: gnat (>= 4.1) gnat 4.6.1 (Arch: all) Depends: gnat-4.6 (>= 4.6.4-2) seems to be solved: the buildds fall back to gnat 4.6 from testing. If anyone can explain why they did complain on the first run, then do this, I am curious.