diff --git a/ChangeLog b/ChangeLog
index 661adffb92..3edcb6b8bf 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Tue Jan 13 22:56:57 2009  Tanaka Akira  <akr@fsij.org>
+
+	* ext/socket/addrinfo.h (AI_NUMERICSERV): defined.
+	  (AI_MASK): add AI_NUMERICSERV.
+
+	* ext/socket/getaddrinfo.c (getaddrinfo): support AI_NUMERICSERV.
+
 Tue Jan 13 21:45:53 2009  Yuki Sonoda (Yugui)  <yugui@yugui.jp>
 
 	* lib/ostruct.rb (OpenStruct#inspect): fixed the recursion check.
diff --git a/ext/socket/addrinfo.h b/ext/socket/addrinfo.h
index f6061f1e26..171d3c2ce7 100644
--- a/ext/socket/addrinfo.h
+++ b/ext/socket/addrinfo.h
@@ -50,6 +50,7 @@
 #undef AI_PASSIVE
 #undef AI_CANONNAME
 #undef AI_NUMERICHOST
+#undef AI_NUMERICSERV
 #undef AI_ALL
 #undef AI_ADDRCONFIG
 #undef AI_V4MAPPED
@@ -107,9 +108,10 @@
 #define	AI_PASSIVE	0x00000001 /* get address to use bind() */
 #define	AI_CANONNAME	0x00000002 /* fill ai_canonname */
 #define	AI_NUMERICHOST	0x00000004 /* prevent name resolution */
+#define	AI_NUMERICSERV	0x00000008 /* prevent service name resolution */
 /* valid flags for addrinfo */
 #ifndef __HAIKU__
-#define	AI_MASK		(AI_PASSIVE | AI_CANONNAME | AI_NUMERICHOST)
+#define	AI_MASK		(AI_PASSIVE | AI_CANONNAME | AI_NUMERICHOST | AI_NUMERICSERV)
 #endif
 
 #define	AI_ALL		0x00000100 /* IPv6 and IPv4-mapped (with AI_V4MAPPED) */
diff --git a/ext/socket/getaddrinfo.c b/ext/socket/getaddrinfo.c
index de16b9fb12..ef01a607be 100644
--- a/ext/socket/getaddrinfo.c
+++ b/ext/socket/getaddrinfo.c
@@ -375,6 +375,8 @@ getaddrinfo(const char *hostname, const char *servname, const struct addrinfo *h
 				pai->ai_protocol = IPPROTO_UDP;
 			}
 			port = htons((unsigned short)atoi(servname));
+                } else if (pai->ai_flags & AI_NUMERICSERV) {
+                        ERR(EAI_NONAME);
 		} else {
 			struct servent *sp;
 			const char *proto;