diff --git a/build.sh b/build.sh
index 067692b..f43b52d 100755
--- a/build.sh
+++ b/build.sh
@@ -520,17 +520,24 @@ mvapich2()
 
     for mpi_comp in ${MPI_COMPILER_mvapich2}
     do
+        echo "Using the ${mpi_comp} compiler"
         MVAPICH2_RPM=${MVAPICH2_NAME}_${mpi_comp}-${MVAPICH2_VER}-${MVAPICH2_REL}.${build_arch}.rpm
         MVAPICH2_PREFIX="${STACK_PREFIX}/mpi/${mpi_comp}/${MVAPICH2_NAME}-${MVAPICH2_VERSION}"
 
         case ${mpi_comp} in
             gcc)
-                MVAPICH2_COMP_ENV="CC=gcc CXX=g++"
-
                 if [ $is_gfortran -eq 1 ]; then
-                    MVAPICH2_COMP_ENV="$MVAPICH2_COMP_ENV F77=gfortran F90=gfortran"
+                    if [ $ARCH = "ppc64" ]; then
+                        MVAPICH2_COMP_ENV='CC="gcc -m64" CXX="g++ -m64" F77="gfortran -m64" F90="gfortran -m64"'
+                    else
+                        MVAPICH2_COMP_ENV="CC=gcc CXX=g++ F77=gfortran F90=gfortran"
+                    fi
                 elif [ $is_gcc_g77 -eq 1 ]; then
-                    MVAPICH2_COMP_ENV="$MVAPICH2_COMP_ENV F77=g77 F90=g77"
+                    if [ $ARCH = "ppc64" ]; then
+                        MVAPICH2_COMP_ENV='CC="gcc -m64" CXX="g++ -m64" F77="g77 -m64" F90=/bin/false'
+                    else
+                        MVAPICH2_COMP_ENV="CC=gcc CXX=g++ F77=g77 F90=/bin/false"
+                    fi
                 fi
             ;;
             pathscale)
@@ -571,6 +578,7 @@ mvapich2()
                --define \'open_ib_home ${STACK_PREFIX}\' \
                --define \'comp_env ${MVAPICH2_COMP_ENV}\' \
                --define \'auto_req 0\' \
+               --define \'mpi_selector ${STACK_PREFIX}/bin/mpi-selector\' \
                --define \'ofa_build 1\' \
                $MVAPICH2_SRC_RPM
         elif [ $MVAPICH2_CONF_impl = "ofa" ] && [ $MVAPICH2_CONF_ckpt -eq 1 ]; then
@@ -589,6 +597,7 @@ mvapich2()
                --define \'open_ib_home ${STACK_PREFIX}\' \
                --define \'comp_env ${MVAPICH2_COMP_ENV}\' \
                --define \'auto_req 0\' \
+               --define \'mpi_selector ${STACK_PREFIX}/bin/mpi-selector\' \
                --define \'ofa_build 1\' \
                $MVAPICH2_SRC_RPM
         elif [ $MVAPICH2_CONF_impl = "udapl" ]; then
@@ -609,6 +618,7 @@ mvapich2()
                --define \'dat_include ${MVAPICH2_DAT_INCLUDE}\' \
                --define \'comp_env ${MVAPICH2_COMP_ENV}\' \
                --define \'auto_req 0\' \
+               --define \'mpi_selector ${STACK_PREFIX}/bin/mpi-selector\' \
                --define \'ofa_build 1\' \
                $MVAPICH2_SRC_RPM
         fi
diff --git a/build_env.sh b/build_env.sh
index 76d68ed..8a4e681 100644
--- a/build_env.sh
+++ b/build_env.sh
@@ -1045,7 +1045,7 @@ mvapich2_config() {
             echo "MVAPICH2_CONF_shared_libs=\"${MVAPICH2_CONF_shared_libs}\"" >> $CONFIG
         fi
 
-        MVAPICH2_CONF_multithread=1
+        MVAPICH2_CONF_multithread=0
 
         if ! ( grep -w MVAPICH2_CONF_multithread $CONFIG > $NULL 2>&1 ); then
             echo "MVAPICH2_CONF_multithread=\"${MVAPICH2_CONF_multithread}\"" >> $CONFIG
