diff --git a/.github/workflows/mcstas-basictest.yml b/.github/workflows/mcstas-basictest.yml
index 3ddf1beeb0..3a11718e3f 100644
--- a/.github/workflows/mcstas-basictest.yml
+++ b/.github/workflows/mcstas-basictest.yml
@@ -381,7 +381,6 @@ jobs:
            fi
            test -n "$(command -v mcstas${EXESUFFIX})"
            mcstas${EXESUFFIX} --version
-           mctest${SUFFIX} --verbose --instr=BNL_H8,ISIS_CRISP,templateSANS_Mantid,NCrystal_example,ESS_BEER_MCPL,Test_MCPL_input,Test_MCPL_output,Test_KDSource,Masked_ESS_butterfly_image --testdir=run_basictests --suffix=${{ matrix.cogen }}_${{ matrix.method }}_${{ matrix.CC || 'default' }} --uid=${MYWORKERID}
            if [ "${{ matrix.nmpi }}" != "0" ];
            then
              mctest${SUFFIX}  --verbose --mpi=${{ matrix.nmpi }} --instr=BNL_H8,ISIS_CRISP,templateSANS_Mantid,NCrystal_example,ESS_BEER_MCPL,Test_MCPL_input,Test_MCPL_output,Test_KDSource,Masked_ESS_butterfly_image --testdir=run_basictests --suffix=${{ matrix.cogen }}_${{ matrix.method }}_${{ matrix.CC || 'default' }}_${{ matrix.mpi }} --uid=${MYWORKERID}
diff --git a/.github/workflows/mcxtrace-basictest.yml b/.github/workflows/mcxtrace-basictest.yml
index 36ded9b846..f56f5bee11 100644
--- a/.github/workflows/mcxtrace-basictest.yml
+++ b/.github/workflows/mcxtrace-basictest.yml
@@ -388,7 +388,6 @@ jobs:
            fi
            test -n "$(command -v mcxtrace${EXESUFFIX})"
            mcxtrace${EXESUFFIX} --version
-           mxtest${SUFFIX} --verbose --instr=JJ_SAXS,ESRF_BM29,Test_MCPL_input,Test_MCPL_output,Test_Absorption --testdir=run_basictests --suffix=${{ matrix.cogen }}_${{ matrix.method }}_${{ matrix.CC || 'default' }} --uid=${MYWORKERID}
            if [ "${{ matrix.nmpi }}" != "0" ];
            then
              mxtest${SUFFIX} --verbose --mpi=${{ matrix.nmpi }} --instr=JJ_SAXS,ESRF_BM29,Test_MCPL_input,Test_MCPL_output,Test_Absorption --testdir=run_basictests --suffix=${{ matrix.cogen }}_${{ matrix.method }}_${{ matrix.CC || 'default' }}_${{ matrix.mpi }} --uid=${MYWORKERID}
diff --git a/tools/Python/mcgui/mcgui.py b/tools/Python/mcgui/mcgui.py
index 2f0b5c8745..b5c6593eca 100755
--- a/tools/Python/mcgui/mcgui.py
+++ b/tools/Python/mcgui/mcgui.py
@@ -215,7 +215,7 @@ def canPlot(self):
         return ((self.__instrFile != "") and (not self.isSimRunning()))
     
     __thread_exc_signal = QtCore.Signal(str)
-    def compile(self, mpi=False):
+    def compile(self, mpi=True):
         # using Qt in-built cross-thread signaling
         self.__thread_exc_signal.connect(handleExceptionMsg)
         
diff --git a/tools/Python/mcgui/widgets.py b/tools/Python/mcgui/widgets.py
index 659545549f..b7772b43c0 100644
--- a/tools/Python/mcgui/widgets.py
+++ b/tools/Python/mcgui/widgets.py
@@ -631,6 +631,8 @@ def retranslateUi(self, dlgStartSim):
         self.cbxClustering.setItemText(4, _translate("dlgStartSim", "OpenACC (recompile)"))
         self.cbxClustering.setItemText(5, _translate("dlgStartSim", "OpenACC and MPI"))
         self.cbxClustering.setItemText(6, _translate("dlgStartSim", "OpenACC and MPI (recompile)"))
+        self.cbxClustering.setCurrentIndex(1)
+    
         self.lblInspect.setText(_translate(     "dlgStartSim", "Inspect:"))
         self.lblAutoPlot.setText(_translate(    "dlgStartSim", "Autoplot:"))
         self.lblAutoPlot.setToolTip(_translate( "dlgStartSim", "Automatically show results with selected plotter at the end"))
diff --git a/tools/Python/mcrun/mcrun.py b/tools/Python/mcrun/mcrun.py
index bc6ed3fc37..723955943a 100644
--- a/tools/Python/mcrun/mcrun.py
+++ b/tools/Python/mcrun/mcrun.py
@@ -248,8 +248,8 @@ def add_mcrun_adv_options(parser):
 
     # Multiprocessing
     add('--mpi',
-        metavar='NB_CPU',
-        help='Spread simulation over NB_CPU machines using MPI')
+        metavar='NB_CPU', default=1,
+        help='Spread simulation over NB_CPU machines using MPI. Compilation with MPI is enabled by default, disable by setting --mpi=None or --mpi=0')
 
     add('--machines',
         metavar='machines',
@@ -429,7 +429,23 @@ def expand_options(options):
 
     # MPI
     if options.mpi is not None:
-        options.use_mpi = True
+        # String-based --mpi input, anything but "None" means enable mpi
+        if isinstance(options.mpi,str):
+            if not (options.mpi.upper()=="NONE"):
+                # Enable
+                options.use_mpi = True
+            else:
+                # Disable
+                options.mpi=None
+                options.use_mpi = False
+        # Numeric --mpi input any value >0 means enable mpi
+        elif not (options.mpi<1):
+            # Enable
+            options.use_mpi = True
+        else:
+            # Disable
+            options.mpi=None
+            options.use_mpi = False
         if options.openacc is True:
             options.cc = mccode_config.compilation['OACC']
         else: