The bug #1206077 was mark as fixed but I found a bug: >>> import lxml.html.diff >>> bug = """<pre><span>foo</span> ... <span>bar</span></pre>""" >>> print("Input `bug`:\n{}\nDiff Output `bug`:\n{}".format(bug, ... lxml.html.diff.htmldiff(bug,bug))) Input `bug`: <pre><span>foo</span> <span>bar</span></pre> Diff Output `bug`: <pre><span>foo</span> <span>bar</span></pre> The diff output should be <pre><span>foo</span> <span>bar</span></pre> If any one can give me a tip of what I should do to fix it I will be happy to try. Raniere