diff --git a/ChangeLog b/ChangeLog
index 1c245b77d1..1553a0741e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Jan 13 12:10:42 2009  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* ext/socket/{getaddrinfo,getnameinfo}.c: need to include ws2tcpip.h
+	  on Windows.
+
 Tue Jan 13 09:49:49 2009  Martin Duerst  <duerst@it.aoyama.ac.jp>
 
 	* ext/socket/socket.c: removed warning about unused variable 'rai'.
diff --git a/ext/socket/getaddrinfo.c b/ext/socket/getaddrinfo.c
index 837a506a72..de16b9fb12 100644
--- a/ext/socket/getaddrinfo.c
+++ b/ext/socket/getaddrinfo.c
@@ -64,6 +64,7 @@
 #include <unistd.h>
 #else
 #include <winsock2.h>
+#include <ws2tcpip.h>
 #include <io.h>
 #endif
 #include <string.h>
diff --git a/ext/socket/getnameinfo.c b/ext/socket/getnameinfo.c
index a77faf9701..689b91c291 100644
--- a/ext/socket/getnameinfo.c
+++ b/ext/socket/getnameinfo.c
@@ -57,6 +57,7 @@
 #endif
 #ifdef _WIN32
 #include <winsock2.h>
+#include <ws2tcpip.h>
 #define snprintf _snprintf
 #endif