diff --git a/datastore_server/source/java/ch/systemsx/cisd/openbis/dss/generic/shared/api/internal/v1/ISearchService.java b/datastore_server/source/java/ch/systemsx/cisd/openbis/dss/generic/shared/api/internal/v1/ISearchService.java
index bf9d7dc41b9be54e94f7d13be64f86e4cf20ffc4..37586e2e93081fe81fbaac6d5266a4b587780062 100644
--- a/datastore_server/source/java/ch/systemsx/cisd/openbis/dss/generic/shared/api/internal/v1/ISearchService.java
+++ b/datastore_server/source/java/ch/systemsx/cisd/openbis/dss/generic/shared/api/internal/v1/ISearchService.java
@@ -104,7 +104,8 @@ public interface ISearchService
     public List<IMaterialImmutable> listMaterials(MaterialIdentifierCollection identifierCollection);
 
     /**
-     * @return a controlled vocabulary with the given code.
+     * @return a controlled vocabulary with the given code. Returns null if the vocabulary with
+     *         given code is not found.
      */
     public IVocabularyImmutable searchForVocabulary(String code);
 }