Sorry, I used wrong email address for first time. I guess, that it is ECL's problem, not IOLib's. I'm loading IOlib in ECL in following Mainer: (let ((*features* (remove :asdf2 *features*))) (asdf:oos 'asdf:load-op :iolib)) I'm using ecl 10.4.1 on 32 bit linux machine: CL-USER> (lisp-implementation-type) "ECL" CL-USER> (lisp-implementation-version) "10.4.1" CL-USER> *features* (:SERVE-EVENT :PROFILE :ASDF2 :ASDF :LINUX :FORMATTER :UINT64-T :UINT32-T :UINT16-T :RELATIVE-PACKAGE-NAMES :UNICODE :DFFI :CLOS-STREAMS :CMU-FORMAT :UNIX :ECL-PDE :DLOPEN :CLOS :THREADS :BOEHM-GC :ANSI-CL :COMMON-LISP :IEEE-FLOATING-POINT :PREFIXED-API :FFI :I686 :COMMON :ECL) Recent SBCL's version (1.0.40) load IOLib just fine, i.e. w/o removing :ASDF2 from *features*. The problem is that SBCL is using more recent ASDF's version: CL-USER> (asdf:asdf-version) "2.003" ans ECL's: (asdf:asdf-version) "1.655" wbr Nikolay P.S. Which cffi version you used? I have my own fork at gitorious.org: http://gitorious.org/~marsijanin/cffi/marsijanins-cffi, but some work need to be done in order to merge with main cffi branch (last time I tried to load iolib with HEAD of the main cffi branch I got some errors about cffi's wrapper/grovel).