diff --git a/src/calibre/ebooks/conversion/utils.py b/src/calibre/ebooks/conversion/utils.py
index 86a4668b9b..4822eee6ae 100644
--- a/src/calibre/ebooks/conversion/utils.py
+++ b/src/calibre/ebooks/conversion/utils.py
@@ -5,7 +5,7 @@ __license__   = 'GPL v3'
 __copyright__ = '2010, Kovid Goyal <kovid@kovidgoyal.net>'
 __docformat__ = 'restructuredtext en'
 
-import re
+import re, error as re_error
 from math import ceil
 from calibre.ebooks.conversion.preprocess import DocAnalysis, Dehyphenator
 from calibre.utils.logging import default_log
@@ -148,7 +148,7 @@ class HeuristicProcessor(object):
         return wordcount.words
 
     def markup_italicis(self, html):
-        self.log.debug("\n\n\nitalicize debugging \n\n\n")
+        #self.log.debug("\n\n\nitalicize debugging \n\n\n")
         ITALICIZE_WORDS = [
             'Etc.', 'etc.', 'viz.', 'ie.', 'i.e.', 'Ie.', 'I.e.', 'eg.',
             'e.g.', 'Eg.', 'E.g.', 'et al.', 'et cetera', 'n.b.', 'N.b.',
@@ -184,6 +184,9 @@ class HeuristicProcessor(object):
                 except OverflowError:
                     # match.group(0) was too large to be compiled into a regex
                     continue
+                except re_error:
+                    # the match was not a valid regular expression
+                    continue
 
         return html