diff --git a/tests/unit_tests/test_mesh_to_vtk.py b/tests/unit_tests/test_mesh_to_vtk.py
index b57235edda..3b7ccf9fa6 100644
--- a/tests/unit_tests/test_mesh_to_vtk.py
+++ b/tests/unit_tests/test_mesh_to_vtk.py
@@ -30,7 +30,7 @@ spherical_mesh.theta_grid = np.linspace(0, np.pi / 2, num=30)
 @pytest.mark.parametrize("mesh", [cylinder_mesh, regular_mesh, rectilinear_mesh, spherical_mesh])
 def test_write_data_to_vtk(mesh, tmpdir):
     # BUILD
-    filename = tmpdir / "out.vtk"
+    filename = Path(tmpdir) / "out.vtk"
 
     data = np.random.random(mesh.num_mesh_cells)