Hello, in order to get GSLL to run on Windows7+CCL+MSYS2+GSL, I needed to customize *cc* and *cc-flags*. Right now, I do this by modifying the code in grovel.lisp, as for *cc-flags*: #+(and windows msys2) (list "-I" "E:/msys64/mingw64/lib/libffi-3.2.1/include/" "-I" "c:/Users/977315/quicklisp/dists/quicklisp/software/cffi_0.14.0/") (I prefer not to modify system-wide environment variables on my PC) I see alternate ways of achieving the same effect: 1. Write own gsll loader that customizes *cc* and *cc-flags* 2. Write own cffi-libffi loader that customizes the variables 3. (somehow) advise gsll or cffi-libffi loaders in my lisp-init files to customize the variables 4. Modify environment variables for my process. What is the advised way to do this? I would prefer 3: in my lisp startup file, I (somehow) write some advice code to asdf that customize *cc* and *cc-flags*. But I don't know how to do that. Thank you, Mirko