diff --git a/internal/sftp/client.go b/internal/sftp/client.go
index c392f7c..93c069e 100644
--- a/internal/sftp/client.go
+++ b/internal/sftp/client.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"net"
 	"os"
+	"strconv"
 	"sync"
 	"time"
 
@@ -157,7 +158,8 @@ func buildClient(config *Config) (*Client, error) {
 		return nil, &ConnectionError{Op: "auth", Err: fmt.Errorf("必须提供密码或密钥文件")}
 	}
 
-	addr := fmt.Sprintf("%s:%d", config.Host, config.Port)
+	// JoinHostPort 保证 IPv6 主机地址被方括号包裹，fmt 拼接对 IPv6 产生非法地址
+	addr := net.JoinHostPort(config.Host, strconv.Itoa(config.Port))
 	// 拨号与认证、SFTP 子系统握手共享同一总超时预算，认证阶段无界挂起由 deadline 掐断
 	deadline := time.Now().Add(connectTimeout)
 	sshConn, err := net.DialTimeout("tcp", addr, connectTimeout)