diff --git a/app/models/concerns/digital_object/index_and_search/index.rb b/app/models/concerns/digital_object/index_and_search/index.rb
index 381ec04ae..d956d3ada 100644
--- a/app/models/concerns/digital_object/index_and_search/index.rb
+++ b/app/models/concerns/digital_object/index_and_search/index.rb
@@ -51,6 +51,7 @@ def to_solr
 
     doc[:search_identifier_sim] << pid
     doc[:search_identifier_sim].push(*identifiers) # Also append all identifiers to the array
+    doc[:search_identifier_sim] << self.doi.sub(/^doi:/, '') if self.doi.present? # Also append DOI to the array
     doc[:search_keyword_teim] << pid
 
     if flattened_dynamic_field_data.present?
diff --git a/spec/models/concerns/digital_object/index_and_search/index_spec.rb b/spec/models/concerns/digital_object/index_and_search/index_spec.rb
new file mode 100644
index 000000000..6547a5a7a
--- /dev/null
+++ b/spec/models/concerns/digital_object/index_and_search/index_spec.rb
@@ -0,0 +1,27 @@
+require 'rails_helper'
+
+describe DigitalObject::IndexAndSearch::Index do
+  let(:pid) { 'cul:12345' }
+  let(:identifiers) { ['id1', 'id2'] }
+  let(:doi) { 'doi:10.7916/sa43-bk43' }
+  let(:doi_without_prefix) { doi.gsub(/^doi:/, '') }
+  let(:project) { Project.new(display_label: 'Sample Project') }
+  let(:digital_object) {
+    DigitalObject::Item.new.tap do |obj|
+      obj.identifiers = identifiers
+      obj.doi = doi
+      allow(obj).to receive(:pid).and_return(pid)
+      allow(obj).to receive(:project).and_return(project)
+    end
+  }
+
+  let(:solr_doc) { digital_object.to_solr }
+
+  describe '#to_solr' do
+    context 'search_identifier_sim field' do
+      it 'sets the expected values' do
+        expect(solr_doc[:search_identifier_sim]).to eq([pid] + identifiers + [doi_without_prefix])
+      end
+    end
+  end
+end