diff --git a/src/calibre/ebooks/conversion/preprocess.py b/src/calibre/ebooks/conversion/preprocess.py
index 4538af96c4..4838e4a054 100644
--- a/src/calibre/ebooks/conversion/preprocess.py
+++ b/src/calibre/ebooks/conversion/preprocess.py
@@ -18,7 +18,6 @@ convert_entities = functools.partial(entity_to_unicode,
             u'<' : '&lt;',
             u'>' : '&gt;',
             u"'" : '&apos;',
-            u'"' : '&quot;',
             u'&' : '&amp;',
         })
 _span_pat = re.compile('<span.*?</span>', re.DOTALL|re.IGNORECASE)