Hi, I have tested using MinGW cross compiling environment (http://mingw-cross-env.nongnu.org) and the initial build failed. To get around this I had to add the following: #include <stddef.h> /* For ptrdiff_h */ to both: src/libicalvcal/libicalvcal.c src/libicalvcal/vcc.c Once done the libs compile and make test passes all tests.