diff --git a/yt/frontends/stream/definitions.py b/yt/frontends/stream/definitions.py
index a995145da1..42b1bf1f2d 100644
--- a/yt/frontends/stream/definitions.py
+++ b/yt/frontends/stream/definitions.py
@@ -61,7 +61,7 @@ def assign_particle_data(ds, pdata, bbox):
             ds.stream_handler.left_edges,
             ds.stream_handler.right_edges,
             ds.stream_handler.dimensions,
-            parent_ids,  # This is a list of lists
+            parent_ids,
             levels,
             num_children,
         )