diff --git a/doc/todo.txt b/doc/todo.txt
index 421bab22..7008cee2 100644
--- a/doc/todo.txt
+++ b/doc/todo.txt
@@ -9,3 +9,5 @@
 - [PYTHON3]
   linkchecker-git/linkcheck/dns/resolver.py:313: DeprecationWarning: in 3.x, __getslice__ has been removed; use __getitem__
   linkcheck.dns.name.Name(linkcheck.dns.name.from_text(socket.gethostname())[1:])
+- [IP] Detect obfuscated IP addresses
+  http://morph3us.org/blog/index.php?/archives/35-Dotless-IP-addresses-and-URL-Obfuscation.html