diff --git a/openmc/tracks.py b/openmc/tracks.py
index 213a0867ec..671aa65cfc 100644
--- a/openmc/tracks.py
+++ b/openmc/tracks.py
@@ -7,6 +7,7 @@ from .checkvalue import check_filetype_version
 from .source import SourceParticle, ParticleType
 
 from pathlib import Path
+
 ParticleTrack = namedtuple('ParticleTrack', ['particle', 'states'])
 ParticleTrack.__doc__ = """\
 Particle track information
@@ -266,7 +267,7 @@ class Tracks(list):
             track.plot(ax)
         return ax
 
-    def write_tracks_to_vtk(self, filename=Path('tracks.vtk')):
+    def write_tracks_to_vtk(self, filename=Path('tracks.vtp')):
         """Creates a VTP file of the tracks
 
         Parameters
diff --git a/tests/unit_tests/test_tracks.py b/tests/unit_tests/test_tracks.py
index d2548be649..5f3940fadd 100644
--- a/tests/unit_tests/test_tracks.py
+++ b/tests/unit_tests/test_tracks.py
@@ -144,6 +144,7 @@ def test_filter(sphere_model, run_in_tmpdir):
 
 
 def test_write_tracks_to_vtk(sphere_model):
+    vtk = pytest.importorskip('vtk')
     # Set maximum number of tracks per process to write
     sphere_model.settings.max_tracks = 25
     sphere_model.settings.photon_transport = True
@@ -152,7 +153,7 @@ def test_write_tracks_to_vtk(sphere_model):
     generate_track_file(sphere_model, tracks=True)
 
     tracks = openmc.Tracks('tracks.h5')
-    filename = tracks.write_tracks_to_vtk('tracks.vtk')
+    polydata = tracks.write_tracks_to_vtk('tracks.vtp')
 
-    assert filename == 'tracks.vtk'
-    assert Path('tracks.vtk').is_file()
+    assert isinstance(polydata, vtk.vtkPolyData)
+    assert Path('tracks.vtp').is_file()