diff --git a/openmc/mesh.py b/openmc/mesh.py
index 1c934996f..8f6cccb80 100644
--- a/openmc/mesh.py
+++ b/openmc/mesh.py
@@ -361,14 +361,14 @@ class RegularMesh(MeshBase):
         n_dim = len(self.dimension)
 
         # Build the cell which will contain the lattice
-        xplanes = [openmc.XPlane(self.lower_left[0], bc[0]),
-                   openmc.XPlane(self.upper_right[0], bc[1])]
+        xplanes = [openmc.XPlane(self.lower_left[0], boundary_type=bc[0]),
+                   openmc.XPlane(self.upper_right[0], boundary_type=bc[1])]
         if n_dim == 1:
-            yplanes = [openmc.YPlane(-1e10, 'reflective'),
-                       openmc.YPlane(1e10, 'reflective')]
+            yplanes = [openmc.YPlane(-1e10, boundary_type='reflective'),
+                       openmc.YPlane(1e10, boundary_type='reflective')]
         else:
-            yplanes = [openmc.YPlane(self.lower_left[1], bc[2]),
-                       openmc.YPlane(self.upper_right[1], bc[3])]
+            yplanes = [openmc.YPlane(self.lower_left[1], boundary_type=bc[2]),
+                       openmc.YPlane(self.upper_right[1], boundary_type=bc[3])]
 
         if n_dim <= 2:
             # Would prefer to have the z ranges be the max supported float, but
@@ -378,11 +378,11 @@ class RegularMesh(MeshBase):
             # inconsistency between what numpy uses as the max float and what
             # Fortran expects for a real(8), so this avoids code complication
             # and achieves the same goal.
-            zplanes = [openmc.ZPlane(-1e10, 'reflective'),
-                       openmc.ZPlane(1e10, 'reflective')]
+            zplanes = [openmc.ZPlane(-1e10, boundary_type='reflective'),
+                       openmc.ZPlane(1e10, boundary_type='reflective')]
         else:
-            zplanes = [openmc.ZPlane(self.lower_left[2], bc[4]),
-                       openmc.ZPlane(self.upper_right[2], bc[5])]
+            zplanes = [openmc.ZPlane(self.lower_left[2], boundary_type=bc[4]),
+                       openmc.ZPlane(self.upper_right[2], boundary_type=bc[5])]
         root_cell = openmc.Cell()
         root_cell.region = ((+xplanes[0] & -xplanes[1]) &
                             (+yplanes[0] & -yplanes[1]) &
diff --git a/tests/regression_tests/photon_production/test.py b/tests/regression_tests/photon_production/test.py
index c20d4487a..f56e83535 100644
--- a/tests/regression_tests/photon_production/test.py
+++ b/tests/regression_tests/photon_production/test.py
@@ -13,9 +13,9 @@ def model():
     model.materials.append(mat)
 
     cyl = openmc.XCylinder(r=1.0, boundary_type='vacuum')
-    x_plane_left = openmc.XPlane(-1.0, 'vacuum')
+    x_plane_left = openmc.XPlane(-1.0, boundary_type='vacuum')
     x_plane_center = openmc.XPlane(1.0)
-    x_plane_right = openmc.XPlane(1.0e9, 'vacuum')
+    x_plane_right = openmc.XPlane(1.0e9, boundary_type='vacuum')
 
     inner_cyl_left = openmc.Cell()
     inner_cyl_right = openmc.Cell()
diff --git a/tests/regression_tests/resonance_scattering/test.py b/tests/regression_tests/resonance_scattering/test.py
index 588ba7c97..e77dd9258 100644
--- a/tests/regression_tests/resonance_scattering/test.py
+++ b/tests/regression_tests/resonance_scattering/test.py
@@ -17,7 +17,7 @@ class ResonanceScatteringTestHarness(PyAPITestHarness):
         mats_file.export_to_xml()
 
         # Geometry
-        dumb_surface = openmc.XPlane(100, 'reflective')
+        dumb_surface = openmc.XPlane(100, boundary_type='reflective')
         c1 = openmc.Cell(cell_id=1, fill=mat, region=-dumb_surface)
         root_univ = openmc.Universe(universe_id=0, cells=[c1])
         geometry = openmc.Geometry(root_univ)