diff --git a/app/models/doi.rb b/app/models/doi.rb
index 02cdcdfdc..42165293b 100644
--- a/app/models/doi.rb
+++ b/app/models/doi.rb
@@ -661,6 +661,7 @@ def as_indexed_json(_options = {})
       "version_ids" => version_ids,
       "version_of_ids" => version_of_ids,
       "primary_title" => Array.wrap(primary_title),
+      "related_doi" => related_dois,
     }
   end