diff --git a/ChangeLog b/ChangeLog
index 9c68bc6404..dc1076e359 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Apr 25 17:56:39 2013  Tanaka Akira  <akr@fsij.org>
+
+	* ext/socket/extconf.rb: Remove obsolete options: ---with-ipv6-lib and
+	  --with-ipv6-libdir.
+
 Thu Apr 25 17:43:49 2013  Tanaka Akira  <akr@fsij.org>
 
 	* ext/socket/extconf.rb: Implement
diff --git a/ext/socket/extconf.rb b/ext/socket/extconf.rb
index 41f48ef4b0..afdb6368f7 100644
--- a/ext/socket/extconf.rb
+++ b/ext/socket/extconf.rb
@@ -409,13 +409,6 @@ EOF
         have_library(ipv6lib = "v6") and "v6d"
       elsif have_macro("_ZETA_MINAMI_INET6", "sys/param.h")
         have_library(ipv6lib = "inet6") and "zeta"
-      elsif ipv6lib = with_config("ipv6-lib")
-        warn <<EOS
---with-ipv6-lib and --with-ipv6-libdir option will be obsolete, use
---with-inet6lib and --with-inet6-{include,lib} options instead.
-EOS
-        find_library(ipv6lib, nil, with_config("ipv6-libdir", ldirs)) and
-          ipv6lib
       elsif have_library("inet6")
         "inet6"
       end