Just another thing that came to my mind. AFAIK unlike ifort/ifx, gfortran does not define macros like _WIN32 depending on the platform you compile on. So, if you use fpm as a build system you have to supply it in the toml file:
[preprocess]
cpp.suffixes = ["F90", "f90"]
cpp.macros = ["_WIN32"]
which makes the fpm.toml platform-dependent, unless you use profiles as discussed here.