diff --git a/jenkins/open-mpi-build-script.sh b/jenkins/open-mpi-build-script.sh
index 71fbc3b..78656f8 100644
--- a/jenkins/open-mpi-build-script.sh
+++ b/jenkins/open-mpi-build-script.sh
@@ -214,7 +214,9 @@ run_example() {
 if test "${MPIRUN_MODE}" != "none"; then
     echo "--> running examples"
     echo "localhost cpu=2" > "${WORKSPACE}/hostfile"
-    mpirun_version=`"${WORKSPACE}/install/bin/mpirun" --version | sed -n 's/.*\([0-9]\+\.[0-9]\+\)\..*/\1/p'`
+    # Note: using perl here because figuring out a portable sed regexp
+    # proved to be a little challenging.
+    mpirun_version=`"${WORKSPACE}/install/bin/mpirun --version | perl -wnE 'say $1 if /mpirun [^\d]*(\d+.\d+)/'`
     echo "--> mpirun version: ${mpirun_version}"
     case ${mpirun_version} in
 	1.*|2.0*)