if you issue the following (available in quicklisp): (asdf:load-system :hu.dwim.zlib) then for the first time it should generate a lisp file, which then gets compiled and loaded. issuing it for the second time shouldn't do anything, but since some revisions it regenerates the lisp file every time. the relevant code is somewhere around here: https://github.com/cffi/cffi/blob/master/src/c2ffi/asdf.lisp#L135 i tried to trace the INPUT-FILES, OUTPUT-FILES, PERFORM, OPERATION-DONE-P methods, but i don't see anything wrong. one unusual thing is that the output of GENERATE-LISP-OP goes into the src/ directory, not to the usual fasl output dir. same applies to GENERATE-SPEC-OP. any ideas how to debug this? or what to look at? -- • attila lendvai • PGP: 963F 5D5F 45C7 DFCD 0A39 -- “For an instant I think I saw. I saw the loneliness of man as a gigantic wave which had been frozen in front of me, held back by the invisible wall of a metaphor.” — Carlos Castaneda (1925–1998), 'Journey to Ixtlan' (1972)