When testing on CMUCL (cmu-snapshot-2013-04__20d_unicode_-linux-x86) every system fails with this error: Error in function KERNEL:CLASS-TYPEP: Class is currently invalid: #<KERNEL::STANDARD-CLASS ASDF/SYSTEM:SYSTEM {585CFA1D}> [Condition of type SIMPLE-ERROR] Looks like an ASDF upgrade problem.