Hello CL-Debian, hello Will (attached is a patch for you). for the next version of dh-lisp, the Lisp debhelper, I plan it to find precompiled FASL files in the package and automatically add a dependency to the CL implementation that is required to load them. But the following is not just a requirement for dh-lisp but is needed if packages want to contain precompiled FASLs. To prevent such a package with precompiled lisp to end up in a stable release without the appropriate implementation, the package has to depend on a specific version of the implementation that is able to read the FASL format. CMUCL: This is easy and needs no modification, as the FASL format is available in the package version. CMUCL 19B has the FASL versions 19B also SBCL: Changes FASL file versions very often still. I sent a patch to the darcs repository of Peter that adds a "Provides: sbcl-fasl-loader-XX" to debian/control, XX being the fasl file version which is determined at build time Clisp: It is the same practice as with SBCL. As Clisp unfortunately has no repository on cl-debian.alioth.debian.org ;-), I attach a patch to this message. GCL: No idea, really, I never touched it and do not know if it breaks binary compatibility now and then. ;-) Depending on foo-fasl-loader-XX will prevent a fasl-providing package from entering testing/stable before the implementation version that provides foo-fasl-loader-XX. It will however not prevent foo-fasl-loader-XX+1 from entering testing, even though packages in testing depend on foo-fasl-loader-XX. But it enables the maintainer to see, that his package is uninstallable in testing, easily, and that the package needs a rebuild to work with a new version of CMUCL/SBCL/Clisp. After all, this shall prevent binary-incompatible packages silently being around in a stable release. Regards, René