diff --git a/indexer/src/main/java/au/org/aodn/esindexer/service/VocabServiceImpl.java b/indexer/src/main/java/au/org/aodn/esindexer/service/VocabServiceImpl.java
index fa926a0d..b4ae7bda 100644
--- a/indexer/src/main/java/au/org/aodn/esindexer/service/VocabServiceImpl.java
+++ b/indexer/src/main/java/au/org/aodn/esindexer/service/VocabServiceImpl.java
@@ -137,7 +137,7 @@ protected <T> VocabModel buildVocabModel(T currentNode, String vocabApiBase, Voc
         } else if (currentNode instanceof TextNode textNode) {
             resourceUri = textNode.asText();
         } else if (currentNode instanceof VocabModel vocabNode) {
-            safeGet(vocabNode::getAbout);
+            resourceUri = safeGet(vocabNode::getAbout);
         }
 
         if (resourceUri == null) {