diff --git a/src/calibre/ebooks/metadata/opf2.py b/src/calibre/ebooks/metadata/opf2.py
index 08aa439007..62e4cd9d59 100644
--- a/src/calibre/ebooks/metadata/opf2.py
+++ b/src/calibre/ebooks/metadata/opf2.py
@@ -20,7 +20,7 @@ from calibre.ebooks.metadata import string_to_authors, MetaInformation, check_is
 from calibre.ebooks.metadata.book.base import Metadata
 from calibre.utils.date import parse_date, isoformat
 from calibre.utils.localization import get_lang, canonicalize_lang
-from calibre import prints, guess_type
+from calibre import prints, guess_type, prepare_string_for_xml
 from calibre.utils.cleantext import clean_ascii_chars, clean_xml_chars
 from calibre.utils.config import tweaks
 
@@ -1120,7 +1120,7 @@ class OPF(object):  # {{{
                 uuid_elem = self.root.attrib[attr]
                 break
         if uuid_elem:
-            matches = self.root.xpath('//*[@id=%r]'%uuid_elem)
+            matches = self.root.xpath('//*[@id="%s"]'%prepare_string_for_xml(uuid_elem, True))
             if matches:
                 for m in matches:
                     raw = m.text
diff --git a/src/calibre/ebooks/oeb/polish/container.py b/src/calibre/ebooks/oeb/polish/container.py
index a6ea5b0186..e342901f91 100644
--- a/src/calibre/ebooks/oeb/polish/container.py
+++ b/src/calibre/ebooks/oeb/polish/container.py
@@ -16,7 +16,7 @@ from future_builtins import zip
 from lxml import etree
 from cssutils import replaceUrls, getUrls
 
-from calibre import CurrentDir
+from calibre import CurrentDir, prepare_string_for_xml
 from calibre.constants import iswindows
 from calibre.customize.ui import (plugin_for_input_format, plugin_for_output_format)
 from calibre.ebooks.chardet import xml_to_unicode
@@ -1103,7 +1103,7 @@ class EpubContainer(Container):
                 package_id = val
                 break
         if package_id is not None:
-            for elem in self.opf_xpath('//*[@id=%r]'%package_id):
+            for elem in self.opf_xpath('//*[@id="%s"]'%prepare_string_for_xml(package_id, True)):
                 if elem.text:
                     raw_unique_identifier = elem.text
                     break