diff --git a/README-en.md b/README-en.md
index 32b5b161..5bc017a1 100644
--- a/README-en.md
+++ b/README-en.md
@@ -30,6 +30,8 @@ Modify configuration file `~/.cow/rc` (OS X or Linux) or `rc.txt` (Windows). A s
 
     # Line starting with # is comment and will be ignored
     # Local proxy listen address
+    # If cow is deployed behind Loadbalancer, you should specified PAC address(eg. foo.bar.com) like this
+    # listen = http://127.0.0.1:7777 foo.bar.com:7777
     listen = http://127.0.0.1:7777
 
     # SOCKS5 parent proxy
diff --git a/README.md b/README.md
index faf3c84c..cea7fb52 100644
--- a/README.md
+++ b/README.md
@@ -40,6 +40,8 @@ COW 的设计目标是自动化，理想情况下用户无需关心哪些网站
     # 配置 HTTP 和 HTTPS 代理时请填入该地址
     # 若配置代理时有对所有协议使用该代理的选项，且你不清楚此选项的含义，请勾选
     # 或者在自动代理配置中填入 http://127.0.0.1:7777/pac
+    # 如果 cow 部署在负载均衡后面, 需要自定义 PAC 地址(例如: foo.bar.com)如下
+    # listen =  http://127.0.0.1:7777  foo.bar.com:7777
     listen = http://127.0.0.1:7777
 
     # SOCKS5 二级代理
diff --git a/error.go b/error.go
index fad75c75..efbe88fd 100644
--- a/error.go
+++ b/error.go
@@ -13,7 +13,7 @@ var headRawTmpl = "HTTP/1.1 {{.CodeReason}}\r\n" +
 	"Connection: keep-alive\r\n" +
 	"Cache-Control: no-cache\r\n" +
 	"Pragma: no-cache\r\n" +
-	"Content-Type: text/html\r\n" +
+	"Content-Type: text/html;charset=utf-8\r\n" +
 	"Content-Length: {{.Length}}\r\n"
 
 var errPageTmpl, headTmpl *template.Template
@@ -31,7 +31,7 @@ func init() {
 		<h1>{{.H1}}</h1>
 		{{.Msg}}
 		<hr />
-		Generated by <i>COW ` + version + `</i> <br />
+		<i>你电脑经过了代理, 如果是非预期记得关闭代理(系统, 终端等)设置</i> <br />
 		Host <i>` + hostName + `</i> <br />
 		{{.T}}
 	</body>
diff --git a/go.mod b/go.mod
new file mode 100644
index 00000000..115eec30
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,12 @@
+module github.com/yujinqiu/cow
+
+go 1.15
+
+require (
+	github.com/aead/chacha20 v0.0.0-20180709150244-8b13a72661da // indirect
+	github.com/cyfdecyf/bufio v0.0.0-20130801052708-9601756e2a6b
+	github.com/cyfdecyf/color v0.0.0-20130827105946-31d518c963d2
+	github.com/cyfdecyf/leakybuf v0.0.0-20140618011800-ffae040843be
+	github.com/shadowsocks/shadowsocks-go v0.0.0-20200409064450-3e585ff90601
+	golang.org/x/crypto v0.0.0-20210616213533-5ff15b29337e // indirect
+)
diff --git a/proxy.go b/proxy.go
index 601ac65e..1daf9aa8 100644
--- a/proxy.go
+++ b/proxy.go
@@ -160,12 +160,14 @@ func (hp *httpProxy) Serve(wg *sync.WaitGroup, quit <-chan struct{}) {
 	}()
 	host, _, _ := net.SplitHostPort(hp.addr)
 	var pacURL string
-	if host == "" || host == "0.0.0.0" {
-		pacURL = fmt.Sprintf("http://<hostip>:%s/pac", hp.port)
-	} else if hp.addrInPAC == "" {
-		pacURL = fmt.Sprintf("http://%s/pac", hp.addr)
-	} else {
+	if hp.addrInPAC != "" {
 		pacURL = fmt.Sprintf("http://%s/pac", hp.addrInPAC)
+	} else {
+		if host == "" || host == "0.0.0.0" {
+			pacURL = fmt.Sprintf("http://<hostip>:%s/pac", hp.port)
+		} else {
+			pacURL = fmt.Sprintf("http://%s/pac", hp.addr)
+		}
 	}
 	info.Printf("COW %s listen http %s, PAC url %s\n", version, hp.addr, pacURL)
 
@@ -343,7 +345,7 @@ func isSelfRequest(r *Request) bool {
 	// But if client PAC setting is using cow server's DNS name, we can't
 	// decide if the request is for cow itself (need reverse lookup).
 	// So if request path seems like getting PAC, simply return true.
-	if r.URL.Path == "/pac" || strings.HasPrefix(r.URL.Path, "/pac?") {
+	if r.URL.Path == "/pac" || r.URL.Path == "/proxy.pac" || strings.HasPrefix(r.URL.Path, "/pac?") {
 		return true
 	}
 	r.URL.ParseHostPort(r.Header.Host)
@@ -361,7 +363,7 @@ func (c *clientConn) serveSelfURL(r *Request) (err error) {
 	if r.Method != "GET" {
 		goto end
 	}
-	if r.URL.Path == "/pac" || strings.HasPrefix(r.URL.Path, "/pac?") {
+	if r.URL.Path == "/pac" || r.URL.Path == "/proxy.pac" || strings.HasPrefix(r.URL.Path, "/pac?") {
 		sendPAC(c)
 		// PAC header contains connection close, send non nil error to close
 		// client connection.