diff --git a/ChangeLog b/ChangeLog
index c371e179c6..9e68d3eabc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon May 13 21:49:17 2013  Tanaka Akira  <akr@fsij.org>
+
+	* ext/socket/extconf.rb: Check socketpair again.
+	  It is required on Unix.
+
 Mon May 13 21:20:32 2013  NAKAMURA Usaku  <usa@ruby-lang.org>
 
 	* win32/win32.c (getipaddrs): use alternamtive interface name if
diff --git a/ext/socket/extconf.rb b/ext/socket/extconf.rb
index a6a86b967a..88e7366e37 100644
--- a/ext/socket/extconf.rb
+++ b/ext/socket/extconf.rb
@@ -426,6 +426,7 @@ EOF
   have_func("hsterror", headers)
   have_func('getipnodebyname("", 0, 0, (int *)0)', headers) # RFC 2553
   have_func('gethostbyname2("", 0)', headers) # RFC 2133
+  have_func("socketpair(0, 0, 0, 0)", headers)
   unless have_func("gethostname((char *)0, 0)", headers)
     have_func("uname((struct utsname *)NULL)", headers)
   end