diff --git a/tests/unit_tests/conftest.py b/tests/unit_tests/conftest.py
index aa28be9c3b..b69ef0b138 100644
--- a/tests/unit_tests/conftest.py
+++ b/tests/unit_tests/conftest.py
@@ -1,6 +1,17 @@
 import openmc
 import pytest
 
+from tests.regression_tests import config
+
+
+@pytest.fixture(scope='module')
+def mpi_intracomm():
+    if config['mpi']:
+        from mpi4py import MPI
+        return MPI.COMM_WORLD
+    else:
+        return None
+
 
 @pytest.fixture(scope='module')
 def uo2():
diff --git a/tests/unit_tests/test_capi.py b/tests/unit_tests/test_capi.py
index ed0bfd441d..c8ad0907c5 100644
--- a/tests/unit_tests/test_capi.py
+++ b/tests/unit_tests/test_capi.py
@@ -50,8 +50,8 @@ def pincell_model():
 
 
 @pytest.fixture(scope='module')
-def capi_init(pincell_model):
-    openmc.capi.init()
+def capi_init(pincell_model, mpi_intracomm):
+    openmc.capi.init(intracomm=mpi_intracomm)
     yield
     openmc.capi.finalize()
 
@@ -408,11 +408,11 @@ def test_mesh(capi_init):
     assert msf.mesh == mesh
 
 
-def test_restart(capi_init):
+def test_restart(capi_init, mpi_intracomm):
     # Finalize and re-init to make internal state consistent with XML.
     openmc.capi.hard_reset()
     openmc.capi.finalize()
-    openmc.capi.init()
+    openmc.capi.init(intracomm=mpi_intracomm)
     openmc.capi.simulation_init()
 
     # Run for 7 batches then write a statepoint.
diff --git a/tests/unit_tests/test_complex_cell_capi.py b/tests/unit_tests/test_complex_cell_capi.py
index 365ce48081..a76fa63076 100644
--- a/tests/unit_tests/test_complex_cell_capi.py
+++ b/tests/unit_tests/test_complex_cell_capi.py
@@ -3,7 +3,7 @@ import openmc.capi
 import pytest
 
 @pytest.fixture(autouse=True)
-def complex_cell(run_in_tmpdir):
+def complex_cell(run_in_tmpdir, mpi_intracomm):
 
     openmc.reset_auto_ids()
 
@@ -74,7 +74,7 @@ def complex_cell(run_in_tmpdir):
     model.export_to_xml()
 
     openmc.capi.finalize()
-    openmc.capi.init()
+    openmc.capi.init(intracomm=mpi_intracomm)
 
     yield