diff --git a/src/calibre/ebooks/conversion/preprocess.py b/src/calibre/ebooks/conversion/preprocess.py
index 5f1407d630..cb2564ec0a 100644
--- a/src/calibre/ebooks/conversion/preprocess.py
+++ b/src/calibre/ebooks/conversion/preprocess.py
@@ -169,7 +169,7 @@ class HTMLPreProcessor(object):
                   (re.compile(ur'\u00a0'), lambda match : ' '),
 
                   # Detect Chapters to match default XPATH in GUI
-                  (re.compile(r'(?=<(/?br|p))(<(/?br|p)[^>]*)?>\s*(?P<chap>(<i><b>|<i>|<b>)?(Chapter|Epilogue|Prologue|Book|Part)\s*(\d+|\w+)?(</i></b>|</i>|</b>)?)(</?p[^>]*>|<br[^>]*>)\n?((?=(<i>)?\s*\w+(\s+\w+)?(</i>)?(<br[^>]*>|</?p[^>]*>))((?P<title>(<i>)?\s*\w+(\s+\w+)?(</i>)?)(<br[^>]*>|</?p[^>]*>)))?', re.IGNORECASE), chap_head),
+                  (re.compile(r'(?=<(/?br|p))(<(/?br|p)[^>]*)?>\s*(?P<chap>(<i><b>|<i>|<b>)?(Chapter|Epilogue|Prologue|Book|Part)\s*([\d\w-]+)?(</i></b>|</i>|</b>)?)(</?p[^>]*>|<br[^>]*>)\n?((?=(<i>)?\s*\w+(\s+\w+)?(</i>)?(<br[^>]*>|</?p[^>]*>))((?P<title>(<i>)?\s*\w+(\s+\w+)?(</i>)?)(<br[^>]*>|</?p[^>]*>)))?', re.IGNORECASE), chap_head),
                   (re.compile(r'(?=<(/?br|p))(<(/?br|p)[^>]*)?>\s*(?P<chap>([A-Z \'"!]{5,})\s*(\d+|\w+)?)(</?p[^>]*>|<br[^>]*>)\n?((?=(<i>)?\s*\w+(\s+\w+)?(</i>)?(<br[^>]*>|</?p[^>]*>))((?P<title>.*)(<br[^>]*>|</?p[^>]*>)))?'), chap_head),
 
                   # Have paragraphs show better