diff --git a/dialer/icmp/dialer.go b/dialer/icmp/dialer.go
index b307522a..dff41ad2 100644
--- a/dialer/icmp/dialer.go
+++ b/dialer/icmp/dialer.go
@@ -133,7 +133,10 @@ func (d *icmpDialer) initSession(ctx context.Context, addr net.Addr, conn net.Pa
 	}
 
 	tlsCfg := d.options.TLSConfig
-	tlsCfg.NextProtos = []string{"h3", "quic/v1"}
+	tlsCfg = tlsCfg.Clone()
+	if len(tlsCfg.NextProtos) == 0 {
+		tlsCfg.NextProtos = []string{"h3", "quic/v1"}
+	}
 
 	session, err := quic.DialEarly(ctx, conn, addr, tlsCfg, quicConfig)
 	if err != nil {
diff --git a/dialer/quic/dialer.go b/dialer/quic/dialer.go
index 857ff5e1..55812787 100644
--- a/dialer/quic/dialer.go
+++ b/dialer/quic/dialer.go
@@ -115,7 +115,10 @@ func (d *quicDialer) initSession(ctx context.Context, addr net.Addr, conn net.Pa
 	}
 
 	tlsCfg := d.options.TLSConfig
-	tlsCfg.NextProtos = []string{"h3", "quic/v1"}
+	tlsCfg = tlsCfg.Clone()
+	if len(tlsCfg.NextProtos) == 0 {
+		tlsCfg.NextProtos = []string{"h3", "quic/v1"}
+	}
 
 	session, err := quic.DialEarly(ctx, conn, addr, tlsCfg, quicConfig)
 	if err != nil {
diff --git a/listener/quic/listener.go b/listener/quic/listener.go
index 455cc748..4f71d1cb 100644
--- a/listener/quic/listener.go
+++ b/listener/quic/listener.go
@@ -110,7 +110,10 @@ func (l *quicListener) Init(md md.Metadata) (err error) {
 	}
 
 	tlsCfg := l.options.TLSConfig
-	tlsCfg.NextProtos = []string{"h3", "quic/v1"}
+	tlsCfg = tlsCfg.Clone()
+	if len(tlsCfg.NextProtos) == 0 {
+		tlsCfg.NextProtos = []string{"h3", "quic/v1"}
+	}
 
 	ln, err := quic.ListenEarly(conn, tlsCfg, config)
 	if err != nil {