diff --git a/docs/KNOWN_BUGS b/docs/KNOWN_BUGS
index f9305fc42d7ff0d49658c9fa47b7d5ee092dd801..ed28c645ae636800cd9d3fb06ef15e0444a93483 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!
 
+* IPv6 support on AIX 4.3.3 doesn't work due to a missing sockaddr_storage
+  struct. It has been reported to work on AIX 5.1 though.
+
 * Running 'make test' on Mac OS X gives 4 errors. This seems to be related
   to some kind of libtool problem:
   http://curl.haxx.se/mail/archive-2002-03/0029.html and