System is unknown to cmake MINGW64_NT-6.3-9600

I get the following message every time I make a project in MSYS2 on Windows 8.1 (64-bit)…

System is unknown to cmake, create:
Platform/MINGW64_NT-6.3-9600 to use this system, please post your config file on discourse.cmake.org so it can be added to cmake

…Which config file should I post?

Thanks!

Nevermind. Fixed by installing & running the (non-msys) cmake binary which is appropriate for the current (mingw) environment.