diff --git a/proxy.go b/proxy.go
index ef2c12a..b23a260 100644
--- a/proxy.go
+++ b/proxy.go
@@ -23,9 +23,9 @@ func NewProxyConn(proxyUrl string, protocol clientProtocol) (ProxyConn, error) {
 	}
 	switch u.Scheme {
 	case "socks5":
-		return &Socks5Client{u, protocol}, nil
+		return NewSocks5Client(u, protocol), nil
 	case "http":
-		return &HttpClient{u, protocol, nil}, nil
+		return NewHttpClient(u, protocol), nil
 	default:
 		return &DefaultClient{}, nil
 	}
@@ -62,15 +62,20 @@ type clientProtocol struct {
 type Socks5Client struct {
 	proxyUrl *url.URL
 	clientProtocol
+	forward proxy.Dialer
+}
+
+func NewSocks5Client(proxyUrl *url.URL, protocol clientProtocol) *Socks5Client {
+	c := &Socks5Client{proxyUrl, protocol, nil}
+	if c.transport == "quic" {
+		c.forward = NewQuicDialer([]string{c.quicProtocol})
+	}
+	return c
 }
 
 // Socks5 implementation of ProxyConn
 func (s5 *Socks5Client) Dial(network string, address string, timeout time.Duration) (net.Conn, error) {
-	var forward proxy.Dialer
-	if s5.transport == "quic" {
-		forward = NewQuicDialer([]string{s5.quicProtocol})
-	}
-	d, err := proxy.FromURL(s5.proxyUrl, forward)
+	d, err := proxy.FromURL(s5.proxyUrl, s5.forward)
 	if err != nil {
 		return nil, err
 	}
@@ -84,6 +89,14 @@ type HttpClient struct {
 	qd *QuicDialer
 }
 
+func NewHttpClient(proxyUrl *url.URL, protocol clientProtocol) *HttpClient {
+	c := &HttpClient{proxyUrl, protocol, nil}
+	if c.transport == "quic" {
+		c.qd = NewQuicDialer([]string{c.quicProtocol})
+	}
+	return c
+}
+
 func SetHTTPProxyBasicAuth(req *http.Request, username, password string) {
 	auth := username + ":" + password
 	authEncoded := base64.StdEncoding.EncodeToString([]byte(auth))
@@ -100,9 +113,6 @@ func (hc *HttpClient) Dial(network string, address string, timeout time.Duration
 	SetHTTPProxyBasicAuth(req, hc.proxyUrl.User.Username(), password)
 	var proxyConn net.Conn
 	if hc.transport == "quic" {
-		if hc.qd == nil {
-			hc.qd = NewQuicDialer([]string{hc.quicProtocol})
-		}
 		proxyConn, err = hc.qd.Dial(network, hc.proxyUrl.Host)
 	} else {
 		proxyConn, err = net.DialTimeout("tcp", hc.proxyUrl.Host, timeout)
diff --git a/quic.go b/quic.go
index b6d5dfa..b6a6263 100644
--- a/quic.go
+++ b/quic.go
@@ -5,7 +5,7 @@ import (
 	"github.com/quic-go/quic-go"
 	"golang.org/x/net/context"
 	"net"
-	"sync"
+	"runtime"
 	"sync/atomic"
 )
 
@@ -13,7 +13,6 @@ type QuicDialer struct {
 	NextProtos []string
 	streams    atomic.Uint32
 	c          quic.Connection
-	dialing    sync.RWMutex
 }
 
 func NewQuicDialer(nextProtos []string) *QuicDialer {
@@ -28,23 +27,25 @@ func (d *QuicDialer) DialContext(ctx context.Context, network, address string) (
 	now := d.streams.Add(1)
 	if now > maxStreams {
 		// wait for dialing
-		d.dialing.RLock()
-		d.dialing.RUnlock()
+		for {
+			if d.streams.Load() < maxStreams {
+				break
+			}
+			runtime.Gosched()
+		}
 		return d.DialContext(ctx, network, address)
 	}
-	if now == maxStreams+1 || now == 1 {
-		d.dialing.Lock()
+	if now == maxStreams || now == 1 {
 		c, err := quic.DialAddr(ctx, address, &tls.Config{
 			InsecureSkipVerify: true,
 			NextProtos:         d.NextProtos,
 		}, nil)
 		if err != nil {
-			d.dialing.Unlock()
+			d.streams.Store(0)
 			return nil, err
 		}
 		d.c = c
 		d.streams.Store(1)
-		d.dialing.Unlock()
 	}
 	if d.c == nil {
 		// still in initial dialing