Hi, Since I ran into this problem with guile-yamlpp today, I went ahead and implemented Z572's suggestion.
It still feels wrong to do this on a per-package basis (shouldn't `with-extension' take care of setting up the path?), but hey ho. I needed the fallback (as suggested by Z572), else tests would fail (as predicted by Tomas). Like this, the whole chain works for me; in my case: (computed-file "test" (with-extensions (list guile-yamlpp) #~(use-modules (yamlpp)))) Patch incoming. Cheers, Timo