diff --git a/src/calibre/ebooks/conversion/preprocess.py b/src/calibre/ebooks/conversion/preprocess.py
index 4838e4a054..a2ec2912cb 100644
--- a/src/calibre/ebooks/conversion/preprocess.py
+++ b/src/calibre/ebooks/conversion/preprocess.py
@@ -17,7 +17,6 @@ convert_entities = functools.partial(entity_to_unicode,
         result_exceptions = {
             u'<' : '&lt;',
             u'>' : '&gt;',
-            u"'" : '&apos;',
             u'&' : '&amp;',
         })
 _span_pat = re.compile('<span.*?</span>', re.DOTALL|re.IGNORECASE)