diff --git a/mammalps/visualization/generate_visualization_videos.py b/mammalps/visualization/generate_visualization_videos.py
index 31c4e29..c535a31 100644
--- a/mammalps/visualization/generate_visualization_videos.py
+++ b/mammalps/visualization/generate_visualization_videos.py
@@ -120,7 +120,7 @@ class IDs, and additional metadata (e.g., species, activity, actions).
             ]
         )
     elif color_by == "individual":
-        class_id == track_id
+        class_id = track_id
     activity = np.array(
         [
             (