diff --git a/ext/socket/tcpsocket.c b/ext/socket/tcpsocket.c
index 29a3eda45f..f3fcee781d 100644
--- a/ext/socket/tcpsocket.c
+++ b/ext/socket/tcpsocket.c
@@ -59,6 +59,7 @@ tcp_sockaddr(struct sockaddr *addr, socklen_t len)
 static VALUE
 tcp_s_gethostbyname(VALUE obj, VALUE host)
 {
+    rb_warn("TCPSocket.gethostbyname is deprecated; use Addrinfo.getaddrinfo instead.");
     struct rb_addrinfo *res =
 	rsock_addrinfo(host, Qnil, AF_UNSPEC, SOCK_STREAM, AI_CANONNAME);
     return rsock_make_hostent(host, res, tcp_sockaddr);