diff --git a/celerpy/model/output.py b/celerpy/model/output.py
index eb4ef0c..70a59d8 100644
--- a/celerpy/model/output.py
+++ b/celerpy/model/output.py
@@ -67,7 +67,7 @@ class BihSizes(_Model):
     """Bounding Interval Hierarchy tree sizes."""
 
     bboxes: NonNegativeInt
-    inner_nodes: NonNegativeInt
+    internal_nodes: NonNegativeInt
     leaf_nodes: NonNegativeInt
     local_volume_ids: NonNegativeInt
 
@@ -79,6 +79,7 @@ class BihMetadata(_Model):
     num_finite_bboxes: list[NonNegativeInt]
     num_infinite_bboxes: list[NonNegativeInt]
     depth: list[NonNegativeInt]
+    structure: Optional[list[dict]] = None
 
 
 # orange/OrangeParamsOutput.hh
diff --git a/test/test_model.py b/test/test_model.py
index 70b75b8..22d819e 100644
--- a/test/test_model.py
+++ b/test/test_model.py
@@ -51,8 +51,8 @@ def test_orange_stats_serialization():
 
 def test_bih_load():
     result = moutput.BihSizes.model_validate_json(
-        '{"bboxes":8,"inner_nodes":0,"leaf_nodes":1,"local_volume_ids":7}'
+        '{"bboxes":8,"internal_nodes":0,"leaf_nodes":1,"local_volume_ids":7}'
     )
     assert result == moutput.BihSizes(
-        bboxes=8, inner_nodes=0, leaf_nodes=1, local_volume_ids=7
+        bboxes=8, internal_nodes=0, leaf_nodes=1, local_volume_ids=7
     )