Hi, some problem I have with this: (defsystem ... (cffi-grovel:wrapper-file "...") ... generates a call: gcc -m32 -fPIC -o *.dll *.c -shared but cygwin want at least flag `-mno-cygwin'. It would be possible to define this flag in some variable, but the flag is added to the end of the list of arguments - and it just not work. I try this format: gcc cpu-flags cc-flags platform-library-flags* -o output-file input-file by reimplement `cc-compile-and-link' function: ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; (in-package :cffi-grovel) (defun cc-compile-and-link (input-file output-file &key library) (apply #'invoke (or (getenv "CC") *cc*) *cpu-word-size-flags* `(,@*cc-flags* ,@(when library *platform-library-flags*) "-o" ,(native-namestring output-file) ,(native-namestring input-file)))) (setf *cc* "C:/dev/cygwin/bin/gcc-3.exe") ;; its my (setf *cc-flags* '()) ;; remove -fPIC (setf *cpu-word-size-flags* "") ;; and this too (setf *platform-library-flags* '("-mno-cygwin" "-shared")) ;; added -mno-cygwin in begin ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; It is normal, or I don't understand something?