diff --git a/docs/KNOWN_BUGS b/docs/KNOWN_BUGS
index 85885fcf9a38f68bed340dd52ce12e62f2a220d4..a97fd7a2d34efef6cfb6ad4f0b93b0f6dd02cc0a 100644
--- a/docs/KNOWN_BUGS
+++ b/docs/KNOWN_BUGS
@@ -3,6 +3,9 @@ join in and help us correct one or more of these! Also be sure to check the
 changelog of the current development status, as one or more of these problems
 may have been fixed since this was written!
 
+43. There seems to be a problem when connecting to the Microsoft telnet server.
+  http://curl.haxx.se/bug/view.cgi?id=1720605
+
 41. When doing an operation over FTP that requires the ACCT command (but not
   when logging in), the operation will fail since libcurl doesn't detect this
   and thus fails to issue the correct command: