diff --git a/invenio_vocabularies/contrib/subjects/nvs/datastreams.py b/invenio_vocabularies/contrib/subjects/nvs/datastreams.py
index 34d2ea97..6446a763 100644
--- a/invenio_vocabularies/contrib/subjects/nvs/datastreams.py
+++ b/invenio_vocabularies/contrib/subjects/nvs/datastreams.py
@@ -70,7 +70,7 @@ def _transform_entry(self, subject, rdf_graph):
         subject_data = self._get_subject_data(rdf_graph, subject)
         deprecated = subject_data.get(str(rdflib.namespace.OWL.deprecated), [False])
         if deprecated and str(deprecated[0]).lower() == "true":
-            return None  # Skip deprecated subjects
+            raise TransformerError(f"Skipping deprecated subject: {subject_data}")
 
         notation = subject_data.get(str(self.skos_core.notation), [])
         if notation: