diff --git a/kloppy/domain/models/tracking.py b/kloppy/domain/models/tracking.py
index 940692f5..ffae5f11 100644
--- a/kloppy/domain/models/tracking.py
+++ b/kloppy/domain/models/tracking.py
@@ -45,8 +45,8 @@ class Trajectory:
     """
 
     trackable_object: Union[Player, str]
-    start_frame: int
-    end_frame: int
+    start_frame: "Frame"
+    end_frame: "Frame"
     detections: List[Detection]
 
     def __iter__(self):
@@ -158,19 +158,19 @@ def trajectories(self, trackable_object: Union[Player, Literal["ball"]]):
                     # a new trajectory
                     current_trajectory = Trajectory(
                         trackable_object=trackable_object,
-                        start_frame=frame.frame_id,
-                        end_frame=frame.frame_id,
+                        start_frame=frame,
+                        end_frame=frame,
                         detections=[detection],
                     )
                 elif (
                     frame.prev_record is not None
                     and frame.prev_record.frame_id
-                    == current_trajectory.end_frame
+                    == current_trajectory.end_frame.frame_id
                     and frame.prev_record.period.id == frame.period.id
                 ):
                     # and it was tracked in the previous frame --> extend the
                     # current trajectory
-                    current_trajectory.end_frame = frame.frame_id
+                    current_trajectory.end_frame = frame
                     current_trajectory.detections.append(detection)
                 else:
                     # but a frame is missing or a new period started --> finish
@@ -178,8 +178,8 @@ def trajectories(self, trackable_object: Union[Player, Literal["ball"]]):
                     trajectories.append(current_trajectory)
                     current_trajectory = Trajectory(
                         trackable_object=trackable_object,
-                        start_frame=frame.frame_id,
-                        end_frame=frame.frame_id,
+                        start_frame=frame,
+                        end_frame=frame,
                         detections=[detection],
                     )
             else:
diff --git a/kloppy/tests/test_tracking.py b/kloppy/tests/test_tracking.py
index e7a8710f..bfd801ba 100644
--- a/kloppy/tests/test_tracking.py
+++ b/kloppy/tests/test_tracking.py
@@ -184,8 +184,8 @@ def test_trajectories(self):
 
         ball_trajectories = dataset.trajectories("ball")
         assert len(ball_trajectories) == 1
-        assert ball_trajectories[0].start_frame == 0
-        assert ball_trajectories[0].end_frame == 124
+        assert ball_trajectories[0].start_frame.frame_id == 0
+        assert ball_trajectories[0].end_frame.frame_id == 124
         assert len(ball_trajectories[0].detections) == 125
         assert ball_trajectories[0].detections[0] == Detection(
             coordinates=Point3D(x=0, y=0, z=0)
@@ -193,8 +193,8 @@ def test_trajectories(self):
 
         player_trajectories = dataset.trajectories("home_1")
         assert len(player_trajectories) == 2
-        assert player_trajectories[0].start_frame == 0
-        assert player_trajectories[0].end_frame == 9
+        assert player_trajectories[0].start_frame.frame_id == 0
+        assert player_trajectories[0].end_frame.frame_id == 9
         assert len(player_trajectories[0].detections) == 10
         assert player_trajectories[0].detections[0] == Detection(
             coordinates=Point(x=0, y=0)