diff --git a/ocrd/utils.py b/ocrd/utils.py
index 59cf5a30b..5754afdeb 100644
--- a/ocrd/utils.py
+++ b/ocrd/utils.py
@@ -75,10 +75,10 @@ def xmllint_format(xml):
     from lxml import etree as ET
     parser = ET.XMLParser(resolve_entities=False, strip_cdata=False, remove_blank_text=True)
     document = ET.fromstring(xml, parser)
-    return '%s\n%s' % (
+    return ('%s\n%s' % (
         '<?xml version="1.0" encoding="UTF-8"?>',
         ET.tostring(document, pretty_print=True)
-    )
+    )).encode('utf-8')
 
 def is_string(val):
     # pylint: disable=undefined-variable