diff --git a/ChangeLog b/ChangeLog
index 65c26ffd71..dc6d12dafe 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Jun 13 05:32:13 2013  Eric Hodel  <drbrain@segment7.net>
+
+	* ext/socket/extconf.rb:  Enable RFC 3542 IPV6 socket options for OS X
+	  10.7+.  [ruby-trunk - Bug #8517]
+
 Thu Jun 13 00:17:18 2013  Tanaka Akira  <akr@fsij.org>
 
 	* bignum.c (rb_integer_unpack_2comp): New function.
diff --git a/ext/socket/extconf.rb b/ext/socket/extconf.rb
index 458871fbd9..f3be5862f0 100644
--- a/ext/socket/extconf.rb
+++ b/ext/socket/extconf.rb
@@ -294,6 +294,11 @@ end
 
 $INCFLAGS << " -I$(topdir) -I$(top_srcdir)"
 
+if /darwin/ =~ RUBY_PLATFORM
+  # For IPv6 extension header access on OS X 10.7+ [Bug #8517]
+  $CFLAGS << " -D__APPLE_USE_RFC_3542"
+end
+
 headers = []
 unless $mswin or $mingw
   headers = %w<sys/types.h netdb.h string.h sys/socket.h netinet/in.h>