diff --git a/transport/kcptun/client.go b/transport/kcptun/client.go
index 56d7f39e..578b77b0 100644
--- a/transport/kcptun/client.go
+++ b/transport/kcptun/client.go
@@ -62,6 +62,7 @@ func (c *Client) createConn(ctx context.Context, dial DialFn) (*smux.Session, er
 	convid := randv2.Uint32()
 	kcpconn, err := kcp.NewConn4(convid, addr, c.block, config.DataShard, config.ParityShard, true, conn)
 	if err != nil {
+		_ = conn.Close()
 		return nil, err
 	}
 	kcpconn.SetStreamMode(true)
@@ -86,6 +87,7 @@ func (c *Client) createConn(ctx context.Context, dial DialFn) (*smux.Session, er
 	}
 
 	if err := smux.VerifyConfig(smuxConfig); err != nil {
+		_ = kcpconn.Close()
 		return nil, err
 	}
 
diff --git a/transport/kcptun/server.go b/transport/kcptun/server.go
index 91d311ce..a0a137f7 100644
--- a/transport/kcptun/server.go
+++ b/transport/kcptun/server.go
@@ -64,6 +64,7 @@ func (s *Server) Serve(pc net.PacketConn, handler func(net.Conn)) error {
 
 			mux, err := smux.Server(netConn, smuxConfig)
 			if err != nil {
+				_ = netConn.Close()
 				return
 			}
 			defer mux.Close()