I am trying to add directories for #include directives and for linking libraries. The below text is my make.lisp file for building my code: (require 'cmp) (setf c:*user-cc-flags* "-DWXUSINGDLL") (setf c::*ecl-include-directory* "C:/Dave/wx/include,C:/Dave/wx/include/msvc") (setf c::*ecl-library-directory* "C:/Dave/wx/lib/vc_x64_dll") (compile-file "wx.lisp" :system-p t) (c:build-fasl "wx" :lisp-files '("wx.obj")) Although (setf c:*user-cc-flags* "-DWXUSINGDLL") Is working as evidenced by the argument list to run-program, there is no evidence that the include or library directories are being used at all. Moreover, the #include directive in the wx.lisp code cannot find the specified header file. How are c::*ecl-include-directory* and c::*ecl-library-directory* intended to be used? Dave