diff --git a/src/calibre/ebooks/html/__init__.py b/src/calibre/ebooks/html/__init__.py
index d37f1f1f96..720ff711e6 100644
--- a/src/calibre/ebooks/html/__init__.py
+++ b/src/calibre/ebooks/html/__init__.py
@@ -5,27 +5,3 @@ from __future__ import absolute_import, division, print_function, unicode_litera
 __license__   = 'GPL v3'
 __copyright__ = '2009, Kovid Goyal <kovid@kovidgoyal.net>'
 __docformat__ = 'restructuredtext en'
-
-import re
-
-
-def tostring(root, strip_comments=False, pretty_print=False):
-    '''
-    Serialize processed XHTML.
-    '''
-    from lxml.etree import tostring as _tostring
-
-    root.set('xmlns', 'http://www.w3.org/1999/xhtml')
-    root.set('{http://www.w3.org/1999/xhtml}xlink', 'http://www.w3.org/1999/xlink')
-    for x in root.iter():
-        if hasattr(x.tag, 'rpartition') and x.tag.rpartition('}')[-1].lower() == 'svg':
-            x.set('xmlns', 'http://www.w3.org/2000/svg')
-
-    ans = _tostring(root, encoding='utf-8', pretty_print=pretty_print)
-    if strip_comments:
-        ans = re.compile(r'<!--.*?-->', re.DOTALL).sub('', ans)
-    ans = '<?xml version="1.0" encoding="utf-8" ?>\n'+ans
-
-    return ans
-
-