diff --git a/ChangeLog b/ChangeLog
index 0a997ff3e4..6c85258b32 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Tue Jan 29 09:26:20 2013  Shugo Maeda  <shugo@ruby-lang.org>
+
+	* ext/socket/socket.c (sock_s_pack_sockaddr_un): calculate the
+	  correct address length of an abstract socket.
+
+	* test/socket/test_unix.rb: related test.
+
 Mon Jan 28 18:02:16 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* vm_backtrace.c (rb_debug_inspector_frame_{class,binding,iseq}_get):
diff --git a/ext/socket/socket.c b/ext/socket/socket.c
index 09c22d6d69..6900dbcca6 100644
--- a/ext/socket/socket.c
+++ b/ext/socket/socket.c
@@ -1430,7 +1430,7 @@ sock_s_pack_sockaddr_un(VALUE self, VALUE path)
             (size_t)RSTRING_LEN(path), sizeof(sockaddr.sun_path));
     }
     memcpy(sockaddr.sun_path, RSTRING_PTR(path), RSTRING_LEN(path));
-    addr = rb_str_new((char*)&sockaddr, sizeof(sockaddr));
+    addr = rb_str_new((char*)&sockaddr, rsock_unix_sockaddr_len(path));
     OBJ_INFECT(addr, path);
 
     return addr;
diff --git a/test/socket/test_unix.rb b/test/socket/test_unix.rb
index a44ef2de38..90f641efe5 100644
--- a/test/socket/test_unix.rb
+++ b/test/socket/test_unix.rb
@@ -339,10 +339,12 @@ class TestSocket_UNIXSocket < Test::Unit::TestCase
     assert_raise(ArgumentError) { UNIXServer.new("a" * 300) }
   end
 
-  #def test_nul
-  #  # path may contain NULs for abstract unix sockets.  [ruby-core:10288]
-  #  assert_raise(ArgumentError) { Socket.sockaddr_un("a\0b") }
-  #end
+  def test_abstract_namespace
+    return if /linux/ !~ RUBY_PLATFORM
+    addr = Socket.pack_sockaddr_un("\0foo")
+    assert_match(/\0foo\z/, addr)
+    assert_equal("\0foo", Socket.unpack_sockaddr_un(addr))
+  end
 
   def test_dgram_pair
     s1, s2 = UNIXSocket.pair(Socket::SOCK_DGRAM)