diff --git a/client.go b/client.go
index e5c7df8..f49b8fd 100644
--- a/client.go
+++ b/client.go
@@ -283,7 +283,27 @@ func (d *Dialer) DialContext(ctx context.Context, urlStr string, requestHeader h
 		if err != nil {
 			return nil, nil, err
 		}
+
+		getDefaultDialerFunc := func() (netDialerFunc, error) {
+			dialer, err := proxy.FromURL(proxyURL, netDial)
+			if err != nil {
+				return nil, err
+			}
+			if d, ok := dialer.(proxy.ContextDialer); ok {
+				return d.DialContext, nil
+			} else {
+				return func(ctx context.Context, network, addr string) (net.Conn, error) {
+					return dialer.Dial(network, addr)
+				}, nil
+			}
+		}
+
 		switch {
+		case proxyURL.Scheme == "socks5":
+			netDial, err = getDefaultDialerFunc()
+			if err != nil {
+				return nil, nil, err
+			}
 		case proxyURL == nil:
 			// Do nothing. Not using a proxy.
 		case u.Scheme == "http":
@@ -296,17 +316,10 @@ func (d *Dialer) DialContext(ctx context.Context, urlStr string, requestHeader h
 		case u.Scheme == "https":
 			netDial = (&httpsProxyDialer{proxyURL: proxyURL, forwardDial: netDial}).DialContext
 		default:
-			dialer, err := proxy.FromURL(proxyURL, netDial)
+			netDial, err = getDefaultDialerFunc()
 			if err != nil {
 				return nil, nil, err
 			}
-			if d, ok := dialer.(proxy.ContextDialer); ok {
-				netDial = d.DialContext
-			} else {
-				netDial = func(ctx context.Context, network, addr string) (net.Conn, error) {
-					return dialer.Dial(network, addr)
-				}
-			}
 		}
 	}
 
diff --git a/client_server_test.go b/client_server_test.go
index 610fbe2..678be10 100644
--- a/client_server_test.go
+++ b/client_server_test.go
@@ -173,24 +173,19 @@ func TestProxyDial(t *testing.T) {
 	cstDialer := cstDialer // make local copy for modification on next line.
 	cstDialer.Proxy = http.ProxyURL(surl)
 
-	connect := false
 	origHandler := s.Server.Config.Handler
 
 	// Capture the request Host header.
 	s.Server.Config.Handler = http.HandlerFunc(
 		func(w http.ResponseWriter, r *http.Request) {
 			if r.Method == http.MethodConnect {
-				connect = true
+				// HTTPS_PROXY comes here.
 				w.WriteHeader(http.StatusOK)
-				return
 			}
 
-			if !connect {
-				t.Log("connect not received")
-				http.Error(w, "connect not received", http.StatusMethodNotAllowed)
-				return
-			}
+			// HTTP_PROXY comes here.
 			origHandler.ServeHTTP(w, r)
+			return
 		})
 
 	ws, _, err := cstDialer.Dial(s.URL, nil)
@@ -211,7 +206,6 @@ func TestProxyAuthorizationDial(t *testing.T) {
 	cstDialer := cstDialer // make local copy for modification on next line.
 	cstDialer.Proxy = http.ProxyURL(surl)
 
-	connect := false
 	origHandler := s.Server.Config.Handler
 
 	// Capture the request Host header.
@@ -219,17 +213,22 @@ func TestProxyAuthorizationDial(t *testing.T) {
 		func(w http.ResponseWriter, r *http.Request) {
 			proxyAuth := r.Header.Get("Proxy-Authorization")
 			expectedProxyAuth := "Basic " + base64.StdEncoding.EncodeToString([]byte("username:password"))
-			if r.Method == http.MethodConnect && proxyAuth == expectedProxyAuth {
-				connect = true
-				w.WriteHeader(http.StatusOK)
+			if proxyAuth != expectedProxyAuth {
+				msg := fmt.Sprintf("expected proxy authorization is %q, but %q is given", expectedProxyAuth, proxyAuth)
+
+				t.Log(msg)
+				http.Error(
+					w,
+					msg,
+					http.StatusProxyAuthRequired,
+				)
 				return
 			}
 
-			if !connect {
-				t.Log("connect with proxy authorization not received")
-				http.Error(w, "connect with proxy authorization not received", http.StatusMethodNotAllowed)
-				return
+			if r.Method == http.MethodConnect {
+				w.WriteHeader(http.StatusOK)
 			}
+
 			origHandler.ServeHTTP(w, r)
 		})