diff --git a/lib/relaton_bib/document_identifier.rb b/lib/relaton_bib/document_identifier.rb
index 41db6ba..e8f67a4 100644
--- a/lib/relaton_bib/document_identifier.rb
+++ b/lib/relaton_bib/document_identifier.rb
@@ -61,7 +61,7 @@ def to_xml(**opts) # rubocop:disable Metrics/AbcSize, Metrics/CyclomaticComplexi
               id.sub %r{(?<=:)(?:\w{2},)*?(#{opts[:lang]})(?:,\w{2})*}, '\1'
             else id
             end
-      element = opts[:builder].docidentifier lid
+      element = opts[:builder].docidentifier { |b| b.parent.inner_html = lid }
       element[:type] = type if type
       element[:scope] = scope if scope
       element[:primary] = primary if primary
diff --git a/lib/relaton_bib/version.rb b/lib/relaton_bib/version.rb
index eea705f..a1c6bcd 100644
--- a/lib/relaton_bib/version.rb
+++ b/lib/relaton_bib/version.rb
@@ -1,3 +1,3 @@
 module RelatonBib
-  VERSION = "1.18.2".freeze
+  VERSION = "1.18.3".freeze
 end
diff --git a/spec/relaton_bib/document_identifier_spec.rb b/spec/relaton_bib/document_identifier_spec.rb
index d3334c4..c0a30a9 100644
--- a/spec/relaton_bib/document_identifier_spec.rb
+++ b/spec/relaton_bib/document_identifier_spec.rb
@@ -21,7 +21,7 @@
     context "ISO" do
       subject do
         RelatonBib::DocumentIdentifier.new(
-          type: "URN", id: "urn:iso:std:iso:1111:-1:stage-60.60:ed-1:v1:en,fr"
+          type: "URN", id: "urn:iso:std:iso:1111:-1:stage-60.60:ed-1:v1:en,fr",
         )
       end
 
@@ -35,20 +35,18 @@
       subject do
         RelatonBib::DocumentIdentifier.new(
           type: "URN",
-          id: "urn:iec:std:iec:61058-2-4:1995::csv:en:plus:amd:1:2003"
+          id: "urn:iec:std:iec:61058-2-4:1995::csv:en:plus:amd:1:2003",
         )
       end
 
       it "remove part" do
         subject.remove_part
-        expect(subject.id).to eq "urn:iec:std:iec:61058:1995::csv:en:plus:"\
-        "amd:1:2003"
+        expect(subject.id).to eq "urn:iec:std:iec:61058:1995::csv:en:plus:amd:1:2003"
       end
 
       it "remove date" do
         subject.remove_date
-        expect(subject.id).to eq "urn:iec:std:iec:61058-2-4:::csv:en:plus:"\
-        "amd:1:2003"
+        expect(subject.id).to eq "urn:iec:std:iec:61058-2-4:::csv:en:plus:amd:1:2003"
       end
 
       it "set all parts" do
@@ -60,8 +58,7 @@
 
   context "GB" do
     subject do
-      RelatonBib::DocumentIdentifier.new(id: "1111.2-2014",
-                                         type: "Chinese Standard")
+      RelatonBib::DocumentIdentifier.new(id: "1111.2-2014", type: "Chinese Standard")
     end
 
     it "remove part" do
@@ -74,4 +71,14 @@
       expect(subject.id).to eq "1111.2"
     end
   end
+
+  context "#to_xml" do
+    it "with superscription" do
+      subject = RelatonBib::DocumentIdentifier.new(id: "CIPM 43<sup>e</sup> réunion (1950)", type: "BIPM")
+      xml = Nokogiri::XML::Builder.new do |builder|
+        subject.to_xml(builder: builder, lang: "en")
+      end.doc.root
+      expect(xml.to_xml).to eq "<docidentifier type=\"BIPM\">CIPM 43<sup>e</sup> r&#xE9;union (1950)</docidentifier>"
+    end
+  end
 end