diff --git a/websocketproxy.go b/websocketproxy.go
index 29f5bda..63d39ba 100644
--- a/websocketproxy.go
+++ b/websocketproxy.go
@@ -97,6 +97,9 @@ func (w *WebsocketProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 	for _, cookie := range req.Header[http.CanonicalHeaderKey("Cookie")] {
 		requestHeader.Add("Cookie", cookie)
 	}
+	if req.Host != "" {
+		requestHeader.Set("Host", req.Host)
+	}
 
 	// Pass X-Forwarded-For headers too, code below is a part of
 	// httputil.ReverseProxy. See http://en.wikipedia.org/wiki/X-Forwarded-For
diff --git a/websocketproxy_test.go b/websocketproxy_test.go
index 63f7861..b90e02b 100644
--- a/websocketproxy_test.go
+++ b/websocketproxy_test.go
@@ -45,6 +45,12 @@ func TestProxy(t *testing.T) {
 	go func() {
 		mux2 := http.NewServeMux()
 		mux2.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+			// Don't upgrade if original host header isn't preserved
+			if r.Host !=  "127.0.0.1:7777" {
+				log.Printf("Host header set incorrectly.  Expecting 127.0.0.1:7777 got %s", r.Host)
+				return
+			}
+
 			conn, err := upgrader.Upgrade(w, r, nil)
 			if err != nil {
 				log.Println(err)