Greetings All, Seems I needed to use the download script for the prerequisites. Check in the docs you clearly hint at this but this should be updated to you need to build gcc this way. I and a lot of people will probably may get confused by this. Anyhow I get this now for one of the mpfr tests and searched around, there is very little documentation on this and how to link the libraries properly for a build. ERROR! The versions of gmp.h (6.1) and libgmp (6.1.2) do not match. The possible causes are: * A bad configuration in your include/library search paths. * An inconsistency in the include/library search paths of your development environment; an example: http://gcc.gnu.org/ml/gcc-help/2010-11/msg00359.html * GMP has been upgraded after the first "make check". In such a case, try again after a "make clean". * A new or non-standard version naming is used in GMP. In this case, a patch may already be available on the MPFR web site. Otherwise please report the problem. In the first two cases, this may lead to errors, in particular with MPFR. If some other tests fail, please solve that problem first. FAIL tversion (exit status: 1) The only thing I was able to find was this which seems like a workaround rather than an actual fix: https://github.com/JuliaLang/julia/issues/6527 What is the actual fix to gcc linking to my system's mpfr rather it's own internal one as this is breaking the tester.There is nothing at least from my scanning of the FAQ for installing gcc from source that explains this problem other than a few flags, what is the easiest way to fix this? Cheers, Nick