diff --git a/app/models/base.rb b/app/models/base.rb
index 508f4464..a2f771f7 100644
--- a/app/models/base.rb
+++ b/app/models/base.rb
@@ -303,7 +303,7 @@ def self.get_crossref_metadata(id)
       "@id" => id,
       "@type" => type,
       "datePublished" => date_published,
-      "registrantId" => "crossref.#{meta['member']}",
+      "registrantId" => meta["member"].present? ? "crossref.#{meta['member']}" : nil,
     }.compact
   end