diff --git a/run_configs/gcom/build_gcom_ar.py b/run_configs/gcom/build_gcom_ar.py
index 5c71e13e..c52a2048 100755
--- a/run_configs/gcom/build_gcom_ar.py
+++ b/run_configs/gcom/build_gcom_ar.py
@@ -15,7 +15,7 @@
 if __name__ == '__main__':
 
     with BuildConfig(project_label='gcom object archive $compiler',
-                     mpi=False, openmp=False, tool_box=ToolBox()) as state:
+                     mpi=True, openmp=False, tool_box=ToolBox()) as state:
         common_build_steps(state)
         archive_objects(state, output_fpath='$output/libgcom.a')
         cleanup_prebuilds(state, all_unused=True)
diff --git a/run_configs/gcom/build_gcom_so.py b/run_configs/gcom/build_gcom_so.py
index d7ea718a..a5110536 100755
--- a/run_configs/gcom/build_gcom_so.py
+++ b/run_configs/gcom/build_gcom_so.py
@@ -20,7 +20,7 @@
     parsed_args = arg_parser.parse_args()
 
     with BuildConfig(project_label='gcom shared library $compiler',
-                     mpi=False, openmp=False, tool_box=ToolBox()) as state:
+                     mpi=True, openmp=False, tool_box=ToolBox()) as state:
         common_build_steps(state, fpic=True)
         link_shared_object(state, output_fpath='$output/libgcom.so')
         cleanup_prebuilds(state, all_unused=True)
diff --git a/run_configs/gcom/grab_gcom.py b/run_configs/gcom/grab_gcom.py
index 7e8a56c5..0b53b9d3 100755
--- a/run_configs/gcom/grab_gcom.py
+++ b/run_configs/gcom/grab_gcom.py
@@ -14,7 +14,7 @@
 
 # we put this here so the two build configs can read its source_root
 grab_config = BuildConfig(project_label=f'gcom_source {revision}',
-                          mpi=False, openmp=False, tool_box=ToolBox())
+                          tool_box=ToolBox())
 
 
 if __name__ == '__main__':
diff --git a/run_configs/lfric/grab_lfric.py b/run_configs/lfric/grab_lfric.py
index 15dcf93d..82a18897 100755
--- a/run_configs/lfric/grab_lfric.py
+++ b/run_configs/lfric/grab_lfric.py
@@ -18,10 +18,10 @@
 tool_box = ToolBox()
 lfric_source_config = BuildConfig(
     project_label=f'lfric source {LFRIC_REVISION}',
-    mpi=False, openmp=False, tool_box=tool_box)
+    tool_box=tool_box)
 gpl_utils_source_config = BuildConfig(
     project_label=f'lfric source {LFRIC_REVISION}',
-    mpi=False, openmp=False, tool_box=tool_box)
+    tool_box=tool_box)
 
 
 if __name__ == '__main__':
diff --git a/run_configs/lfric/gungho.py b/run_configs/lfric/gungho.py
index 4aac5667..7f075c10 100755
--- a/run_configs/lfric/gungho.py
+++ b/run_configs/lfric/gungho.py
@@ -33,7 +33,7 @@
     gpl_utils_source = gpl_utils_source_config.source_root / 'gpl_utils'
 
     with BuildConfig(project_label='gungho $compiler $two_stage',
-                     mpi=False, openmp=False, tool_box=ToolBox()) as state:
+                     mpi=True, openmp=True, tool_box=ToolBox()) as state:
         grab_folder(state, src=lfric_source / 'infrastructure/source/', dst_label='')
         grab_folder(state, src=lfric_source / 'components/driver/source/', dst_label='')
         grab_folder(state, src=lfric_source / 'components' / 'inventory' / 'source', dst_label='')
@@ -87,7 +87,7 @@
             state,
             common_flags=[
                 '-c',
-                '-ffree-line-length-none', '-fopenmp',
+                '-ffree-line-length-none',
                 '-g',
                 '-std=f2008',
 
@@ -104,8 +104,6 @@
         link_exe(
             state,
             flags=[
-                '-fopenmp',
-
                 '-lyaxt', '-lyaxt_c', '-lnetcdff', '-lnetcdf', '-lhdf5',  # EXTERNAL_DYNAMIC_LIBRARIES
                 '-lxios',  # EXTERNAL_STATIC_LIBRARIES
                 '-lstdc++',
diff --git a/run_configs/lfric/mesh_tools.py b/run_configs/lfric/mesh_tools.py
index d1eb1acc..fde5b793 100755
--- a/run_configs/lfric/mesh_tools.py
+++ b/run_configs/lfric/mesh_tools.py
@@ -25,7 +25,7 @@
     psyclone_overrides = Path(__file__).parent / 'mesh_tools_overrides'
 
     with BuildConfig(project_label='mesh tools $compiler $two_stage',
-                     mpi=False, openmp=False, tool_box=ToolBox()) as state:
+                     mpi=True, openmp=False, tool_box=ToolBox()) as state:
         grab_folder(state, src=lfric_source / 'infrastructure/source/', dst_label='')
         grab_folder(state, src=lfric_source / 'mesh_tools/source/', dst_label='')
         grab_folder(state, src=lfric_source / 'components/science/source/', dst_label='')
diff --git a/run_configs/tiny_fortran/build_tiny_fortran.py b/run_configs/tiny_fortran/build_tiny_fortran.py
index cccd1339..09a6ad49 100755
--- a/run_configs/tiny_fortran/build_tiny_fortran.py
+++ b/run_configs/tiny_fortran/build_tiny_fortran.py
@@ -31,7 +31,7 @@ def __init__(self):
     tool_box.add_tool(Linker(compiler=fc))
 
     with BuildConfig(project_label='tiny_fortran $compiler',
-                     mpi=False, openmp=False, tool_box=tool_box) as state:
+                     tool_box=tool_box) as state:
         git_checkout(state, src='https://github.com/metomi/fab-test-data.git',
                      revision='main', dst_label='src')
 
diff --git a/run_configs/um/build_um.py b/run_configs/um/build_um.py
index 5cc84087..4cf38e4c 100755
--- a/run_configs/um/build_um.py
+++ b/run_configs/um/build_um.py
@@ -124,9 +124,11 @@ def replace_in_file(inpath, outpath, find, replace):
     revision = 'vn12.1'
     um_revision = revision.replace('vn', 'um')
 
+    # The original build script disabled openmp, so for now
+    # we keep this disabled.
     state = BuildConfig(
         project_label=f'um atmos safe {revision} $compiler $two_stage',
-        mpi=False, openmp=False, tool_box=ToolBox())
+        mpi=True, openmp=False, tool_box=ToolBox())
 
     # compiler-specific flags
     compiler = state.tool_box[Category.FORTRAN_COMPILER]
diff --git a/source/fab/build_config.py b/source/fab/build_config.py
index 930d890a..5dfd1309 100644
--- a/source/fab/build_config.py
+++ b/source/fab/build_config.py
@@ -42,8 +42,8 @@ class BuildConfig():
     """
     def __init__(self, project_label: str,
                  tool_box: ToolBox,
-                 mpi: bool,
-                 openmp: bool,
+                 mpi: bool = False,
+                 openmp: bool = False,
                  multiprocessing: bool = True,
                  n_procs: Optional[int] = None,
                  reuse_artefacts: bool = False,
diff --git a/tests/system_tests/CFortranInterop/test_CFortranInterop.py b/tests/system_tests/CFortranInterop/test_CFortranInterop.py
index 86753426..d667506b 100644
--- a/tests/system_tests/CFortranInterop/test_CFortranInterop.py
+++ b/tests/system_tests/CFortranInterop/test_CFortranInterop.py
@@ -27,8 +27,7 @@ def test_CFortranInterop(tmp_path):
 
     # build
     with BuildConfig(fab_workspace=tmp_path, project_label='foo',
-                     mpi=False, openmp=False, tool_box=ToolBox(),
-                     multiprocessing=False) as config:
+                     tool_box=ToolBox(), multiprocessing=False) as config:
         grab_folder(config, src=PROJECT_SOURCE)
         find_source_files(config)
         c_pragma_injector(config)
diff --git a/tests/system_tests/CUserHeader/test_CUserHeader.py b/tests/system_tests/CUserHeader/test_CUserHeader.py
index f5894956..8c3878b0 100644
--- a/tests/system_tests/CUserHeader/test_CUserHeader.py
+++ b/tests/system_tests/CUserHeader/test_CUserHeader.py
@@ -24,8 +24,7 @@ def test_CUseHeader(tmp_path):
 
     # build
     with BuildConfig(fab_workspace=tmp_path, tool_box=ToolBox(),
-                     mpi=False, openmp=False, project_label='foo',
-                     multiprocessing=False) as config:
+                     project_label='foo', multiprocessing=False) as config:
 
         grab_folder(config, PROJECT_SOURCE)
         find_source_files(config)
diff --git a/tests/system_tests/FortranDependencies/test_FortranDependencies.py b/tests/system_tests/FortranDependencies/test_FortranDependencies.py
index 86113351..98aff404 100644
--- a/tests/system_tests/FortranDependencies/test_FortranDependencies.py
+++ b/tests/system_tests/FortranDependencies/test_FortranDependencies.py
@@ -25,7 +25,6 @@ def test_fortran_dependencies(tmp_path):
 
     # build
     with BuildConfig(fab_workspace=tmp_path, tool_box=ToolBox(),
-                     mpi=False, openmp=False,
                      project_label='foo', multiprocessing=False) as config:
         grab_folder(config, src=Path(__file__).parent / 'project-source')
         find_source_files(config)
diff --git a/tests/system_tests/FortranPreProcess/test_FortranPreProcess.py b/tests/system_tests/FortranPreProcess/test_FortranPreProcess.py
index 6992bc37..2081e9de 100644
--- a/tests/system_tests/FortranPreProcess/test_FortranPreProcess.py
+++ b/tests/system_tests/FortranPreProcess/test_FortranPreProcess.py
@@ -22,8 +22,7 @@
 
 def build(fab_workspace, fpp_flags=None):
     with BuildConfig(fab_workspace=fab_workspace, tool_box=ToolBox(),
-                     mpi=False, openmp=False, project_label='foo',
-                     multiprocessing=False) as config:
+                     project_label='foo', multiprocessing=False) as config:
         grab_folder(config, Path(__file__).parent / 'project-source')
         find_source_files(config)
         preprocess_fortran(config, common_flags=fpp_flags)
diff --git a/tests/system_tests/MinimalC/test_MinimalC.py b/tests/system_tests/MinimalC/test_MinimalC.py
index b59566d5..471e48b0 100644
--- a/tests/system_tests/MinimalC/test_MinimalC.py
+++ b/tests/system_tests/MinimalC/test_MinimalC.py
@@ -24,8 +24,7 @@ def test_minimal_c(tmp_path):
 
     # build
     with BuildConfig(fab_workspace=tmp_path, tool_box=ToolBox(),
-                     mpi=False, openmp=False, project_label='foo',
-                     multiprocessing=False) as config:
+                     project_label='foo', multiprocessing=False) as config:
 
         grab_folder(config, PROJECT_SOURCE)
         find_source_files(config)
diff --git a/tests/system_tests/MinimalFortran/test_MinimalFortran.py b/tests/system_tests/MinimalFortran/test_MinimalFortran.py
index df97c0fe..71e58ae4 100644
--- a/tests/system_tests/MinimalFortran/test_MinimalFortran.py
+++ b/tests/system_tests/MinimalFortran/test_MinimalFortran.py
@@ -25,8 +25,7 @@ def test_minimal_fortran(tmp_path):
 
     # build
     with BuildConfig(fab_workspace=tmp_path, tool_box=ToolBox(),
-                     mpi=False, openmp=False, project_label='foo',
-                     multiprocessing=False) as config:
+                     project_label='foo', multiprocessing=False) as config:
         grab_folder(config, PROJECT_SOURCE)
         find_source_files(config)
         preprocess_fortran(config)
diff --git a/tests/system_tests/git/test_git.py b/tests/system_tests/git/test_git.py
index 2f1a0889..d343c7e8 100644
--- a/tests/system_tests/git/test_git.py
+++ b/tests/system_tests/git/test_git.py
@@ -29,8 +29,7 @@
 
 @pytest.fixture
 def config(tmp_path):
-    return BuildConfig('proj', ToolBox(), mpi=False, openmp=False,
-                       fab_workspace=tmp_path)
+    return BuildConfig('proj', ToolBox(), fab_workspace=tmp_path)
 
 
 class TestGitCheckout:
diff --git a/tests/system_tests/incremental_fortran/test_incremental_fortran.py b/tests/system_tests/incremental_fortran/test_incremental_fortran.py
index 9f614899..acde2066 100644
--- a/tests/system_tests/incremental_fortran/test_incremental_fortran.py
+++ b/tests/system_tests/incremental_fortran/test_incremental_fortran.py
@@ -38,14 +38,14 @@ class TestIncremental():
     def config(self, tmp_path):  # tmp_path is a pytest fixture which differs per test, per run
         logging.getLogger('fab').setLevel(logging.WARNING)
 
-        with BuildConfig(project_label=PROJECT_LABEL, mpi=False, openmp=False,
-                         tool_box=ToolBox(), fab_workspace=tmp_path,
+        with BuildConfig(project_label=PROJECT_LABEL, tool_box=ToolBox(),
+                         fab_workspace=tmp_path,
                          multiprocessing=False) as grab_config:
             grab_folder(grab_config, Path(__file__).parent / 'project-source',
                         dst_label='src')
 
-        build_config = BuildConfig(project_label=PROJECT_LABEL, mpi=False,
-                                   openmp=False, tool_box=ToolBox(),
+        build_config = BuildConfig(project_label=PROJECT_LABEL,
+                                   tool_box=ToolBox(),
                                    fab_workspace=tmp_path,
                                    multiprocessing=False)
 
@@ -246,8 +246,7 @@ class TestCleanupPrebuilds():
     @pytest.mark.parametrize("kwargs,expect", in_out)
     def test_clean(self, tmp_path, kwargs, expect):
 
-        with BuildConfig(project_label=PROJECT_LABEL, mpi=False, openmp=False,
-                         tool_box=ToolBox(),
+        with BuildConfig(project_label=PROJECT_LABEL, tool_box=ToolBox(),
                          fab_workspace=tmp_path, multiprocessing=False) as config:
             remaining = self._prune(config, kwargs=kwargs)
 
@@ -257,8 +256,8 @@ def test_prune_unused(self, tmp_path):
         # pruning everything not current
 
         current_prebuilds = ArtefactSet.CURRENT_PREBUILDS
-        with BuildConfig(project_label=PROJECT_LABEL, mpi=False, openmp=False,
-                         tool_box=ToolBox(), fab_workspace=tmp_path,
+        with BuildConfig(project_label=PROJECT_LABEL, tool_box=ToolBox(),
+                         fab_workspace=tmp_path,
                          multiprocessing=False) as config:
             config._artefact_store = {current_prebuilds: {
                 tmp_path / PROJECT_LABEL / BUILD_OUTPUT / PREBUILD / 'a.123.foo',
diff --git a/tests/system_tests/prebuild/test_prebuild.py b/tests/system_tests/prebuild/test_prebuild.py
index 0a04d0c6..492a4832 100644
--- a/tests/system_tests/prebuild/test_prebuild.py
+++ b/tests/system_tests/prebuild/test_prebuild.py
@@ -28,8 +28,7 @@ def build_config(self, fab_workspace, grab_prebuild_folder=None):
 
         with BuildConfig(
                 project_label='test_prebuild', tool_box=ToolBox(),
-                mpi=False, openmp=False, fab_workspace=fab_workspace,
-                multiprocessing=False) as config:
+                fab_workspace=fab_workspace, multiprocessing=False) as config:
             grab_folder(config, Path(__file__).parent / 'project-source',
                         dst_label='src')
             # insert a prebuild grab step or don't insert anything
diff --git a/tests/system_tests/psyclone/test_psyclone_system_test.py b/tests/system_tests/psyclone/test_psyclone_system_test.py
index 14b265d8..cf3c80d0 100644
--- a/tests/system_tests/psyclone/test_psyclone_system_test.py
+++ b/tests/system_tests/psyclone/test_psyclone_system_test.py
@@ -49,8 +49,7 @@ def test_make_parsable_x90(tmp_path):
     parsable_x90_path = make_parsable_x90(input_x90_path)
 
     x90_analyser = X90Analyser()
-    with BuildConfig('proj', ToolBox(), mpi=False, openmp=False,
-                     fab_workspace=tmp_path) as config:
+    with BuildConfig('proj', ToolBox(), fab_workspace=tmp_path) as config:
         x90_analyser._config = config  # todo: code smell
         x90_analyser.run(parsable_x90_path)
 
@@ -74,8 +73,7 @@ class TestX90Analyser:
     def run(self, tmp_path):
         parsable_x90_path = self.expected_analysis_result.fpath
         x90_analyser = X90Analyser()
-        with BuildConfig('proj', ToolBox(), mpi=False, openmp=False,
-                         fab_workspace=tmp_path) as config:
+        with BuildConfig('proj', ToolBox(), fab_workspace=tmp_path) as config:
             x90_analyser._config = config
             analysed_x90, _ = x90_analyser.run(parsable_x90_path)  # type: ignore
             # don't delete the prebuild
@@ -101,7 +99,6 @@ class Test_analysis_for_x90s_and_kernels:
 
     def test_analyse(self, tmp_path):
         with BuildConfig('proj', fab_workspace=tmp_path,
-                         mpi=False, openmp=False,
                          tool_box=ToolBox()) as config:
             analysed_x90 = _analyse_x90s(config, x90s=[SAMPLE_X90])
             all_kernel_hashes = _analyse_kernels(config, kernel_roots=[Path(__file__).parent])
@@ -130,8 +127,8 @@ class TestPsyclone:
     """
     @pytest.fixture
     def config(self, tmp_path):
-        config = BuildConfig('proj', ToolBox(), mpi=False, openmp=False,
-                             fab_workspace=tmp_path, multiprocessing=False)
+        config = BuildConfig('proj', ToolBox(), fab_workspace=tmp_path,
+                             multiprocessing=False)
         return config
 
     def steps(self, config, psyclone_lfric_api):
diff --git a/tests/unit_tests/parse/fortran/test_fortran_analyser.py b/tests/unit_tests/parse/fortran/test_fortran_analyser.py
index cb16c734..75621020 100644
--- a/tests/unit_tests/parse/fortran/test_fortran_analyser.py
+++ b/tests/unit_tests/parse/fortran/test_fortran_analyser.py
@@ -51,8 +51,7 @@ class TestAnalyser:
     @pytest.fixture
     def fortran_analyser(self, tmp_path):
         fortran_analyser = FortranAnalyser()
-        fortran_analyser._config = BuildConfig('proj', ToolBox(), mpi=False,
-                                               openmp=False,
+        fortran_analyser._config = BuildConfig('proj', ToolBox(),
                                                fab_workspace=tmp_path)
         return fortran_analyser
 
diff --git a/tests/unit_tests/steps/test_analyse.py b/tests/unit_tests/steps/test_analyse.py
index c735e774..2cec86df 100644
--- a/tests/unit_tests/steps/test_analyse.py
+++ b/tests/unit_tests/steps/test_analyse.py
@@ -133,8 +133,7 @@ def test_exceptions(self, tmp_path):
              pytest.warns(UserWarning, match="deprecated 'DEPENDS ON:'"):
             # The warning "deprecated 'DEPENDS ON:' comment found in fortran
             # code" is in "def _parse_files" in "source/steps/analyse.py"
-            config = BuildConfig('proj', ToolBox(), mpi=False, openmp=False,
-                                 fab_workspace=tmp_path)
+            config = BuildConfig('proj', ToolBox(), fab_workspace=tmp_path)
 
             # the exception should be suppressed (and logged) and this step
             # should run to completion
diff --git a/tests/unit_tests/steps/test_archive_objects.py b/tests/unit_tests/steps/test_archive_objects.py
index 3c828ab9..30e41781 100644
--- a/tests/unit_tests/steps/test_archive_objects.py
+++ b/tests/unit_tests/steps/test_archive_objects.py
@@ -27,7 +27,7 @@ def test_for_exes(self):
         '''
         targets = ['prog1', 'prog2']
 
-        config = BuildConfig('proj', ToolBox(), mpi=False, openmp=False)
+        config = BuildConfig('proj', ToolBox())
         for target in targets:
             config.artefact_store.update_dict(
                 ArtefactSet.OBJECT_FILES, target,
@@ -58,7 +58,7 @@ def test_for_library(self):
         a shared library.
         '''
 
-        config = BuildConfig('proj', ToolBox(), mpi=False, openmp=False)
+        config = BuildConfig('proj', ToolBox())
         config.artefact_store.update_dict(
             ArtefactSet.OBJECT_FILES, None, {'util1.o', 'util2.o'})
 
@@ -81,7 +81,7 @@ def test_incorrect_tool(self):
         '''Test that an incorrect archive tool is detected
         '''
 
-        config = BuildConfig('proj', ToolBox(), mpi=False, openmp=False)
+        config = BuildConfig('proj', ToolBox())
         tool_box = config.tool_box
         cc = tool_box.get_tool(Category.C_COMPILER, config.mpi)
         # And set its category to C_COMPILER
diff --git a/tests/unit_tests/steps/test_compile_c.py b/tests/unit_tests/steps/test_compile_c.py
index 426f4bf6..8ec687a2 100644
--- a/tests/unit_tests/steps/test_compile_c.py
+++ b/tests/unit_tests/steps/test_compile_c.py
@@ -27,7 +27,7 @@ def fixture_content(tmp_path, tool_box):
     analysed file and expected hash.'''
 
     config = BuildConfig('proj', tool_box, multiprocessing=False,
-                         mpi=False, openmp=False, fab_workspace=tmp_path)
+                         fab_workspace=tmp_path)
 
     analysed_file = AnalysedC(fpath=Path(f'{config.source_root}/foo.c'), file_hash=0)
     config._artefact_store[ArtefactSet.BUILD_TREES] = \
diff --git a/tests/unit_tests/steps/test_compile_fortran.py b/tests/unit_tests/steps/test_compile_fortran.py
index e5587ea3..fd9acabe 100644
--- a/tests/unit_tests/steps/test_compile_fortran.py
+++ b/tests/unit_tests/steps/test_compile_fortran.py
@@ -35,7 +35,7 @@ def fixture_artefact_store(analysed_files):
 def test_compile_cc_wrong_compiler(tool_box):
     '''Test if a non-C compiler is specified as c compiler.
     '''
-    config = BuildConfig('proj', tool_box, mpi=False, openmp=False)
+    config = BuildConfig('proj', tool_box)
     # Take the Fortran compiler
     cc = tool_box[Category.C_COMPILER]
     # And set its category to C_COMPILER
@@ -76,7 +76,7 @@ def test_vanilla(self, analysed_files, tool_box: ToolBox):
         # this gets filled in
         mod_hashes: Dict[str, int] = {}
 
-        config = BuildConfig('proj', tool_box, mpi=False, openmp=False)
+        config = BuildConfig('proj', tool_box)
         mp_common_args = MpCommonArgs(config, FlagsConfig(), {}, True)
         with mock.patch('fab.steps.compile_fortran.run_mp', return_value=run_mp_results):
             with mock.patch('fab.steps.compile_fortran.get_mod_hashes'):
@@ -161,8 +161,7 @@ def fixture_content(tool_box):
     obj_combo_hash = '17ef947fd'
     mods_combo_hash = '10867b4f3'
     mp_common_args = MpCommonArgs(
-        config=BuildConfig('proj', tool_box, mpi=False, openmp=False,
-                           fab_workspace=Path('/fab')),
+        config=BuildConfig('proj', tool_box, fab_workspace=Path('/fab')),
         flags=flags_config,
         mod_hashes={'mod_dep_1': 12345, 'mod_dep_2': 23456},
         syntax_only=False,
@@ -463,7 +462,7 @@ def test_vanilla(self, tool_box):
             mock.Mock(module_defs=['foo', 'bar']),
         }
 
-        config = BuildConfig('proj', tool_box, mpi=False, openmp=False,
+        config = BuildConfig('proj', tool_box, 
                              fab_workspace=Path('/fab_workspace'))
 
         with mock.patch('pathlib.Path.exists', side_effect=[True, True]):
diff --git a/tests/unit_tests/steps/test_preprocess.py b/tests/unit_tests/steps/test_preprocess.py
index 721192c2..38376503 100644
--- a/tests/unit_tests/steps/test_preprocess.py
+++ b/tests/unit_tests/steps/test_preprocess.py
@@ -18,8 +18,7 @@ class Test_preprocess_fortran:
     def test_big_little(self, tmp_path):
         # ensure big F90s are preprocessed and little f90s are copied
 
-        config = BuildConfig('proj', ToolBox(), mpi=False, openmp=False,
-                             fab_workspace=tmp_path)
+        config = BuildConfig('proj', ToolBox(), fab_workspace=tmp_path)
         big_f90 = Path(config.source_root / 'big.F90')
         little_f90 = Path(config.source_root / 'little.f90')
 
diff --git a/tests/unit_tests/steps/test_root_inc_files.py b/tests/unit_tests/steps/test_root_inc_files.py
index b8241678..6c0e94b9 100644
--- a/tests/unit_tests/steps/test_root_inc_files.py
+++ b/tests/unit_tests/steps/test_root_inc_files.py
@@ -15,7 +15,7 @@ def test_vanilla(self):
         # ensure it copies the inc file
         inc_files = [Path('/foo/source/bar.inc')]
 
-        config = BuildConfig('proj', ToolBox(), mpi=False, openmp=False)
+        config = BuildConfig('proj', ToolBox())
         config.artefact_store[ArtefactSet.INITIAL_SOURCE] = inc_files
 
         with mock.patch('fab.steps.root_inc_files.shutil') as mock_shutil:
@@ -29,7 +29,7 @@ def test_vanilla(self):
 
     def test_skip_output_folder(self):
         # ensure it doesn't try to copy a file in the build output
-        config = BuildConfig('proj', ToolBox(), mpi=False, openmp=False)
+        config = BuildConfig('proj', ToolBox())
         inc_files = [Path('/foo/source/bar.inc'),
                      config.build_output / 'fab.inc']
         config.artefact_store[ArtefactSet.INITIAL_SOURCE] = inc_files
@@ -47,7 +47,7 @@ def test_name_clash(self):
         # ensure raises an exception if there is a name clash
         inc_files = [Path('/foo/source/bar.inc'), Path('/foo/sauce/bar.inc')]
 
-        config = BuildConfig('proj', ToolBox(), mpi=False, openmp=False)
+        config = BuildConfig('proj', ToolBox())
         config.artefact_store[ArtefactSet.INITIAL_SOURCE] = inc_files
 
         with pytest.raises(FileExistsError):
diff --git a/tests/unit_tests/test_build_config.py b/tests/unit_tests/test_build_config.py
index 65f04939..b6c01fdd 100644
--- a/tests/unit_tests/test_build_config.py
+++ b/tests/unit_tests/test_build_config.py
@@ -26,8 +26,7 @@ def simple_step(config):
 
     def test_add_cleanup(self):
         # ensure the cleanup step is added
-        with BuildConfig('proj', ToolBox(), mpi=False,
-                         openmp=False) as config:
+        with BuildConfig('proj', ToolBox()) as config:
             assert CLEANUP_COUNT not in config.artefact_store
 
         assert CLEANUP_COUNT in config.artefact_store