Hello. In the cl-test-grid project we test how every library in Quicklisp is compiled and also run some test suites. Then we build reports, review regressions and submit bugs to library authors. It is very often that machine where tests are run don't have some foreign library, of don't have a C compiler. For libraries using cffi-grovel it results in cl:simple-error: External process exited with code 1. (example log: http://cl-test-grid.appspot.com/blob?key=1sisosse6j) This kind of errors are not regressions, so we don't want to report them. It would be very helpful to distinguish such errors automatically, because they are not regressions and we don't need to report them to authors. As this type of errors happens all the time during testing on various machines, automation will save us significant efforts. We could easily distinguish these errors if cffi-grovel signaled specific condition instead of generic cl:simple-error. Possible simple fix is to introduce new condition cffi-grovel:grovel-error and shadow cl:error in the cffi-grovel package, instead writing an own cff-givel:error function with the same prototype as cl:error, but with the condition type it signals will be cffi-grovel:grovel-error. If you agree to this proposal I am willing to provide a patch. Best regards, - Anton