Hi, this is just a heads-up: Version 10 of the gfortran compiler will no longer accept mismatched arguments to old-style Fortran routines, see https://gcc.gnu.org/gcc-10/changes.html and https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91556 Currently, this leads to a configure error with mpich 3.3.1: checking whether gfortran allows mismatched arguments... no configure: error: The Fortran compiler gfortran will not compile files that call the same routine with arguments of different types. There is now a -fallow-argument-mismatch option which degrades the error to a warning, which you may want to put into your configure script. Alternatively, gfortran also provides the ISO_Fortran_binding.h file since its version 9, you might also want to use that. The release of gfortran 10 will be quite some time in the future, so there is no immediate rush. Regards Thomas