diff --git a/oaipmh-core/src/main/java/info/textgrid/middleware/SetDeliverer.java b/oaipmh-core/src/main/java/info/textgrid/middleware/SetDeliverer.java
index cee05cbe31cae44473895e91be6d60c964e4bd02..a3e1a0e770480ff51c5d15876f39768f6fd49705 100644
--- a/oaipmh-core/src/main/java/info/textgrid/middleware/SetDeliverer.java
+++ b/oaipmh-core/src/main/java/info/textgrid/middleware/SetDeliverer.java
@@ -138,8 +138,8 @@ public class SetDeliverer {
 
       AggregationBuilder collectionFilterTerm =
           AggregationBuilders.terms(DH_COLLECTION_FILTER_TERM_NAME)
-              .field("administrativeMetadata.dcterms:identifier")
-              // .script(mergeCollectionIDAndTitle)
+              // .field("administrativeMetadata.dcterms:identifier")
+              .script(mergeCollectionIDAndTitle)
               .size(DH_SIZE);
 
       collectionFilter.subAggregation(collectionFilterTerm);