diff --git a/src/calibre/ebooks/metadata/opf2.py b/src/calibre/ebooks/metadata/opf2.py
index 25d4855980..6ae40d157d 100644
--- a/src/calibre/ebooks/metadata/opf2.py
+++ b/src/calibre/ebooks/metadata/opf2.py
@@ -554,6 +554,8 @@ class OPF(object):  # {{{
                 resolve_entities=True, assume_utf8=True)
         raw = raw[raw.find('<'):]
         self.root     = etree.fromstring(raw, self.PARSER)
+        if self.root is None:
+            raise ValueError('Not an OPF file')
         try:
             self.package_version = float(self.root.get('version', None))
         except (AttributeError, TypeError, ValueError):
diff --git a/src/calibre/ebooks/oeb/reader.py b/src/calibre/ebooks/oeb/reader.py
index cb10b4ccce..b99f5d1087 100644
--- a/src/calibre/ebooks/oeb/reader.py
+++ b/src/calibre/ebooks/oeb/reader.py
@@ -127,7 +127,7 @@ class OEBReader(object):
     def _metadata_from_opf(self, opf):
         from calibre.ebooks.metadata.opf2 import OPF
         from calibre.ebooks.oeb.transforms.metadata import meta_info_to_oeb_metadata
-        stream = cStringIO.StringIO(etree.tostring(opf))
+        stream = cStringIO.StringIO(etree.tostring(opf, xml_declaration=True, encoding='utf-8'))
         mi = OPF(stream).to_book_metadata()
         if not mi.language:
             mi.language = get_lang().replace('_', '-')