diff --git a/gpxtrackposter/track.py b/gpxtrackposter/track.py
index 3874983..ce758b8 100644
--- a/gpxtrackposter/track.py
+++ b/gpxtrackposter/track.py
@@ -142,7 +142,8 @@ def _load_gpx_data(self, gpx: gpxpy.gpx.GPX, timezone_adjuster: typing.Optional[
             for s in t.segments:
                 line = [s2sphere.LatLng.from_degrees(p.latitude, p.longitude) for p in s.points]
                 self.polylines.append(line)
-        self.activity_type = gpx.tracks[0].type.lower()
+        if gpx.tracks[0].type:
+            self.activity_type = gpx.tracks[0].type.lower()
 
     def append(self, other: "Track") -> None:
         """Append other track to self."""