diff --git a/datev_export_xml/models/datev_xml_generator.py b/datev_export_xml/models/datev_xml_generator.py
index 3349988a..4e2e6ea0 100644
--- a/datev_export_xml/models/datev_xml_generator.py
+++ b/datev_export_xml/models/datev_xml_generator.py
@@ -83,7 +83,9 @@ def generate_xml_document(self, invoices, check_xsd=True):
                 "Document_v050.xsd",
             )
 
-        return "document.xml", etree.tostring(root)
+        return "document.xml", etree.tostring(
+            root, xml_declaration=True, encoding="UTF-8"
+        )
 
     @api.model
     def generate_xml_invoice(self, invoice, check_xsd=True):
@@ -102,4 +104,4 @@ def generate_xml_invoice(self, invoice, check_xsd=True):
                 invoice=invoice,
             )
 
-        return doc_name, etree.tostring(root)
+        return doc_name, etree.tostring(root, xml_declaration=True, encoding="UTF-8")
diff --git a/datev_export_xml/tests/test_datev_export.py b/datev_export_xml/tests/test_datev_export.py
index 464021a3..6c8b4815 100644
--- a/datev_export_xml/tests/test_datev_export.py
+++ b/datev_export_xml/tests/test_datev_export.py
@@ -105,9 +105,9 @@ def _check_filecontent(self, export):
             doc_data = z.read(doc_file)
             inv_data = z.read(inv_file)
             # document.xml
-            doc_root = etree.fromstring(doc_data.decode("utf-8"))
+            doc_root = etree.fromstring(doc_data)
             # invoice.xml file
-            inv_root = etree.fromstring(inv_data.decode("utf-8"))
+            inv_root = etree.fromstring(inv_data)
             for i in inv_root:
                 invoice_xml.update(i.attrib)