diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 2b8d1bd634..a46acb85c9 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -89,7 +89,8 @@ jobs:
           . ../firedrake_venv/bin/activate
           python "$(which firedrake-clean)"
           python -m pip install \
-            pytest-xdist pytest-timeout ipympl
+            pytest-xdist pytest-timeout ipympl pytest-split
+          pip install git+https://github.com/JDBetteridge/mpispawn
           python -m pip list
       - name: Test Firedrake Serial
         run: |
@@ -111,36 +112,42 @@ jobs:
           . ../firedrake_venv/bin/activate
           echo OMP_NUM_THREADS is "$OMP_NUM_THREADS"
           echo OPENBLAS_NUM_THREADS is "$OPENBLAS_NUM_THREADS"
-          mpiexec -n 2 python -m pytest \
+          mpispawn -nU 12 -nW 2 --propagate-errcodes pytest \
+            --splits \$MPISPAWN_NUM_TASKS \
+            --group \$MPISPAWN_TASK_ID1 \
             --timeout=1800 \
             --timeout-method=thread \
             -o faulthandler_timeout=1860 \
-            -m "not broken and not slow and parallel[2]" \
-            -sv tests
+            -m "parallel[\$MPISPAWN_WORLD_SIZE] and not broken and not slow" \
+            -v tests
         timeout-minutes: 30
       - name: Test Firedrake 3 ranks
         run: |
           . ../firedrake_venv/bin/activate
           echo OMP_NUM_THREADS is "$OMP_NUM_THREADS"
           echo OPENBLAS_NUM_THREADS is "$OPENBLAS_NUM_THREADS"
-          mpiexec -n 3 python -m pytest \
+          mpispawn -nU 12 -nW 3 --propagate-errcodes pytest \
+            --splits \$MPISPAWN_NUM_TASKS \
+            --group \$MPISPAWN_TASK_ID1 \
             --timeout=1800 \
             --timeout-method=thread \
             -o faulthandler_timeout=1860 \
-            -m "not broken and not slow and parallel[3]" \
-            -sv tests
+            -m "parallel[\$MPISPAWN_WORLD_SIZE] and not broken and not slow" \
+            -v tests
         timeout-minutes: 60
       - name: Test Firedrake 4 ranks
         run: |
           . ../firedrake_venv/bin/activate
           echo OMP_NUM_THREADS is "$OMP_NUM_THREADS"
           echo OPENBLAS_NUM_THREADS is "$OPENBLAS_NUM_THREADS"
-          mpiexec -n 4 python -m pytest \
+          mpispawn -nU 12 -nW 4 --propagate-errcodes pytest \
+            --splits \$MPISPAWN_NUM_TASKS \
+            --group \$MPISPAWN_TASK_ID1 \
             --timeout=1800 \
             --timeout-method=thread \
             -o faulthandler_timeout=1860 \
-            -m "not broken and not slow and parallel[4]" \
-            -sv tests
+            -m "parallel[\$MPISPAWN_WORLD_SIZE] and not broken and not slow" \
+            -v tests
         timeout-minutes: 30
       - name: Test Firedrake 6 ranks
         run: |
diff --git a/requirements-git.txt b/requirements-git.txt
index b6e9e8e1dd..6d8b3d7019 100644
--- a/requirements-git.txt
+++ b/requirements-git.txt
@@ -5,3 +5,4 @@ git+https://github.com/firedrakeproject/tsfc.git#egg=tsfc
 git+https://github.com/OP2/PyOP2.git#egg=pyop2
 git+https://github.com/dolfin-adjoint/pyadjoint.git#egg=pyadjoint
 git+https://github.com/firedrakeproject/petsc.git@firedrake#egg=petsc
+git+https://github.com/firedrakeproject/pytest-mpi.git@JDBetteridge/spawn#egg=pytest-mpi