diff --git a/tests/regression_tests/periodic/test.py b/tests/regression_tests/periodic/test.py
index f9d26392f2..51a70a6aa7 100644
--- a/tests/regression_tests/periodic/test.py
+++ b/tests/regression_tests/periodic/test.py
@@ -1,58 +1,53 @@
 import openmc
+import pytest
 
 from tests.testing_harness import PyAPITestHarness
 
 
-class PeriodicTest(PyAPITestHarness):
-    def _build_inputs(self):
-        # Define materials
-        water = openmc.Material(1)
-        water.add_nuclide('H1', 2.0)
-        water.add_nuclide('O16', 1.0)
-        water.add_s_alpha_beta('c_H_in_H2O')
-        water.set_density('g/cc', 1.0)
+@pytest.fixture
+def box_model():
+    model = openmc.model.Model()
+    # Define materials
+    water = openmc.Material()
+    water.add_nuclide('H1', 2.0)
+    water.add_nuclide('O16', 1.0)
+    water.add_s_alpha_beta('c_H_in_H2O')
+    water.set_density('g/cc', 1.0)
 
-        fuel = openmc.Material(2)
-        fuel.add_nuclide('U235', 1.0)
-        fuel.set_density('g/cc', 4.5)
+    fuel = openmc.Material()
+    fuel.add_nuclide('U235', 1.0)
+    fuel.set_density('g/cc', 4.5)
 
-        materials = openmc.Materials((water, fuel))
-        materials.default_temperature = '294K'
-        materials.export_to_xml()
+    # Define geometry
+    x_min = openmc.XPlane(surface_id=1, x0=0., boundary_type='periodic')
+    x_max = openmc.XPlane(surface_id=2, x0=5., boundary_type='reflective')
 
-        # Define geometry
-        x_min = openmc.XPlane(surface_id=1, x0=0., boundary_type='periodic')
-        x_max = openmc.XPlane(surface_id=2, x0=5., boundary_type='reflective')
+    y_min = openmc.YPlane(surface_id=3, y0=0., boundary_type='periodic')
+    y_max = openmc.YPlane(surface_id=4, y0=5., boundary_type='reflective')
+    y_min.periodic_surface = x_min
 
-        y_min = openmc.YPlane(surface_id=3, y0=0., boundary_type='periodic')
-        y_max = openmc.YPlane(surface_id=4, y0=5., boundary_type='reflective')
-        y_min.periodic_surface = x_min
+    z_min = openmc.ZPlane(surface_id=5, z0=-5., boundary_type='periodic')
+    z_max = openmc.Plane(surface_id=6, a=0, b=0, c=1, d=5.,
+                         boundary_type='periodic')
+    z_cyl = openmc.ZCylinder(surface_id=7, x0=2.5, y0=0., r=2.0)
 
-        z_min = openmc.ZPlane(surface_id=5, z0=-5., boundary_type='periodic')
-        z_max = openmc.Plane(surface_id=6, a=0, b=0, c=1, d=5.,
-                             boundary_type='periodic')
-        z_cyl = openmc.ZCylinder(surface_id=7, x0=2.5, y0=0., r=2.0)
+    outside_cyl = openmc.Cell(1, fill=water, region=(
+        +x_min & -x_max & +y_min & -y_max & +z_min & -z_max & +z_cyl))
+    inside_cyl = openmc.Cell(2, fill=fuel, region=(
+        +y_min & +z_min & -z_max & -z_cyl))
+    root_universe = openmc.Universe(0, cells=(outside_cyl, inside_cyl))
+    model.geometry = openmc.Geometry(root_universe)
 
-        outside_cyl = openmc.Cell(1, fill=water, region=(
-            +x_min & -x_max & +y_min & -y_max & +z_min & -z_max & +z_cyl))
-        inside_cyl = openmc.Cell(2, fill=fuel, region=(
-            +y_min & +z_min & -z_max & -z_cyl))
-        root_universe = openmc.Universe(0, cells=(outside_cyl, inside_cyl))
-
-        geometry = openmc.Geometry()
-        geometry.root_universe = root_universe
-        geometry.export_to_xml()
-
-        # Define settings
-        settings = openmc.Settings()
-        settings.particles = 1000
-        settings.batches = 4
-        settings.inactive = 0
-        settings.source = openmc.Source(space=openmc.stats.Box(
-            (0, 0, 0), (5, 5, 0)))
-        settings.export_to_xml()
+    # Define settings
+    model.settings.particles = 1000
+    model.settings.batches = 4
+    model.settings.inactive = 0
+    model.settings.source = openmc.Source(space=openmc.stats.Box(
+        (0, 0, 0), (5, 5, 0))
+    )
+    return model
 
 
-def test_periodic():
-    harness = PeriodicTest('statepoint.4.h5')
+def test_periodic(box_model):
+    harness = PyAPITestHarness('statepoint.4.h5', box_model)
     harness.main()
diff --git a/tests/regression_tests/periodic_6fold/inputs_true.dat b/tests/regression_tests/periodic_6fold/inputs_true.dat
index 46c2a6ff55..35bbcc0475 100644
--- a/tests/regression_tests/periodic_6fold/inputs_true.dat
+++ b/tests/regression_tests/periodic_6fold/inputs_true.dat
@@ -1,11 +1,11 @@
 <?xml version='1.0' encoding='utf-8'?>
 <geometry>
-  <cell id="1" material="1" region="9 10 -11 12" universe="0" />
-  <cell id="2" material="2" region="9 10 -12" universe="0" />
-  <surface boundary="periodic" coeffs="0.4999999999999999 0.8660254037844387 0.0 0.0" id="9" type="plane" />
-  <surface boundary="periodic" coeffs="0.4999999999999999 -0.8660254037844387 0.0 0.0" id="10" type="plane" />
-  <surface boundary="reflective" coeffs="5.0" id="11" type="x-plane" />
-  <surface coeffs="2.598076211353316 1.4999999999999998 2.0" id="12" type="z-cylinder" />
+  <cell id="1" material="1" region="1 2 -3 4" universe="0" />
+  <cell id="2" material="2" region="1 2 -4" universe="0" />
+  <surface boundary="periodic" coeffs="0.4999999999999999 0.8660254037844387 0.0 0.0" id="1" type="plane" />
+  <surface boundary="periodic" coeffs="0.4999999999999999 -0.8660254037844387 0.0 0.0" id="2" type="plane" />
+  <surface boundary="reflective" coeffs="5.0" id="3" type="x-plane" />
+  <surface coeffs="2.598076211353316 1.4999999999999998 2.0" id="4" type="z-cylinder" />
 </geometry>
 <?xml version='1.0' encoding='utf-8'?>
 <materials>
diff --git a/tests/regression_tests/periodic_6fold/test.py b/tests/regression_tests/periodic_6fold/test.py
index 1f8efdbf71..555ab24f9f 100644
--- a/tests/regression_tests/periodic_6fold/test.py
+++ b/tests/regression_tests/periodic_6fold/test.py
@@ -1,62 +1,59 @@
 import openmc
 import numpy as np
+import pytest
 
 from tests.testing_harness import PyAPITestHarness
 
 
-class Periodic6FoldTest(PyAPITestHarness):
-    def _build_inputs(self):
-        # Define materials
-        water = openmc.Material(1)
-        water.add_nuclide('H1', 2.0)
-        water.add_nuclide('O16', 1.0)
-        water.add_s_alpha_beta('c_H_in_H2O')
-        water.set_density('g/cc', 1.0)
+@pytest.fixture
+def model():
+    model = openmc.model.Model()
 
-        fuel = openmc.Material(2)
-        fuel.add_nuclide('U235', 1.0)
-        fuel.set_density('g/cc', 4.5)
+    # Define materials
+    water = openmc.Material()
+    water.add_nuclide('H1', 2.0)
+    water.add_nuclide('O16', 1.0)
+    water.add_s_alpha_beta('c_H_in_H2O')
+    water.set_density('g/cc', 1.0)
 
-        materials = openmc.Materials((water, fuel))
-        materials.default_temperature = '294K'
-        materials.export_to_xml()
+    fuel = openmc.Material()
+    fuel.add_nuclide('U235', 1.0)
+    fuel.set_density('g/cc', 4.5)
 
-        # Define the geometry.  Note that this geometry is somewhat non-sensical
-        # (it essentially defines a circle of half-cylinders), but it is
-        # designed so that periodic and reflective BCs will give different
-        # answers.
-        theta1 = (-1/6 + 1/2) * np.pi
-        theta2 = (1/6 - 1/2) * np.pi
-        plane1 = openmc.Plane(a=np.cos(theta1), b=np.sin(theta1),
-                              boundary_type='periodic')
-        plane2 = openmc.Plane(a=np.cos(theta2), b=np.sin(theta2),
-                              boundary_type='periodic')
+    # Define the geometry.  Note that this geometry is somewhat non-sensical
+    # (it essentially defines a circle of half-cylinders), but it is
+    # designed so that periodic and reflective BCs will give different
+    # answers.
+    theta1 = (-1/6 + 1/2) * np.pi
+    theta2 = (1/6 - 1/2) * np.pi
+    plane1 = openmc.Plane(a=np.cos(theta1), b=np.sin(theta1),
+                            boundary_type='periodic')
+    plane2 = openmc.Plane(a=np.cos(theta2), b=np.sin(theta2),
+                            boundary_type='periodic')
 
-        x_max = openmc.XPlane(x0=5., boundary_type='reflective')
+    x_max = openmc.XPlane(x0=5., boundary_type='reflective')
 
-        z_cyl = openmc.ZCylinder(x0=3*np.cos(np.pi/6), y0=3*np.sin(np.pi/6),
-                                 r=2.0)
+    z_cyl = openmc.ZCylinder(x0=3*np.cos(np.pi/6), y0=3*np.sin(np.pi/6),
+                                r=2.0)
 
-        outside_cyl = openmc.Cell(1, fill=water, region=(
-            +plane1 & +plane2 & -x_max & +z_cyl))
-        inside_cyl = openmc.Cell(2, fill=fuel, region=(
-            +plane1 & +plane2 & -z_cyl))
-        root_universe = openmc.Universe(0, cells=(outside_cyl, inside_cyl))
+    outside_cyl = openmc.Cell(1, fill=water, region=(
+        +plane1 & +plane2 & -x_max & +z_cyl))
+    inside_cyl = openmc.Cell(2, fill=fuel, region=(
+        +plane1 & +plane2 & -z_cyl))
+    root_universe = openmc.Universe(0, cells=(outside_cyl, inside_cyl))
+    model.geometry = openmc.Geometry(root_universe)
 
-        geometry = openmc.Geometry()
-        geometry.root_universe = root_universe
-        geometry.export_to_xml()
-
-        # Define settings
-        settings = openmc.Settings()
-        settings.particles = 1000
-        settings.batches = 4
-        settings.inactive = 0
-        settings.source = openmc.Source(space=openmc.stats.Box(
-            (0, 0, 0), (5, 5, 0)))
-        settings.export_to_xml()
+    # Define settings
+    model.settings = openmc.Settings()
+    model.settings.particles = 1000
+    model.settings.batches = 4
+    model.settings.inactive = 0
+    model.settings.source = openmc.Source(space=openmc.stats.Box(
+        (0, 0, 0), (5, 5, 0))
+    )
+    return model
 
 
-def test_periodic():
-    harness = Periodic6FoldTest('statepoint.4.h5')
+def test_periodic(model):
+    harness = PyAPITestHarness('statepoint.4.h5', model)
     harness.main()