--- mpich-3.2.1/src/packaging/envmods/mpich.module.in.orig	2017-11-11 03:19:44.000000000 +0100

+++ mpich-3.2.1/src/packaging/envmods/mpich.module.in	2018-04-04 14:14:16.553160669 +0200

@@ -3,12 +3,23 @@

 #  MPICH module for use with 'environment-modules' package:

 # 

+# Only allow one mpi module to be loaded at a time

+conflict mpi

+

 # Define prefix so PATH and MANPATH can be updated.

-setenv        prefix        @prefix@

-setenv        exec_prefix   @exec_prefix@

+setenv        MPI_BIN       @LIBDIR@/bin

+setenv        MPI_SYSCONFIG @sysconfdir@/@MPINAME@-@ARCH@

+setenv        MPI_FORTRAN_MOD_DIR @fortranmoddir@/@MPINAME@

+setenv        MPI_INCLUDE   @includedir@

+setenv        MPI_LIB       @libdir@

+setenv        MPI_MAN       @mandir@

+setenv        MPI_PYTHON_SITEARCH	@py3sitearch@/@MPINAME@

+setenv        MPI_PYTHON2_SITEARCH	@py3sitearch@/@MPINAME@

+setenv        MPI_PYTHON3_SITEARCH	@py3sitearch@/@MPINAME@

+setenv        MPI_COMPILER  @MPINAME@-@ARCH@

+setenv        MPI_SUFFIX    _@MPINAME@

+setenv        MPI_HOME      @LIBDIR@

 prepend-path  PATH          @bindir@

-prepend-path  MANPATH       @mandir@

-

-# Undefine prefix and exec_prefix which are too generic environment variables.

-unsetenv      prefix

-unsetenv      exec_prefix

+prepend-path  LD_LIBRARY_PATH @libdir@

+prepend-path  MANPATH       :@mandir@

+prepend-path  PKG_CONFIG_PATH @LIBDIR@/lib/pkgconfig