diff --git a/crates/shadowsocks/src/net/sys/windows/mod.rs b/crates/shadowsocks/src/net/sys/windows/mod.rs
index cad81836aac3..346f4c95b3a5 100644
--- a/crates/shadowsocks/src/net/sys/windows/mod.rs
+++ b/crates/shadowsocks/src/net/sys/windows/mod.rs
@@ -8,8 +8,7 @@ use std::{
         io::{AsRawSocket, FromRawSocket, IntoRawSocket, RawSocket},
     },
     pin::Pin,
-    ptr,
-    slice,
+    ptr, slice,
     task::{self, Poll},
     time::{Duration, Instant},
 };
@@ -26,35 +25,18 @@ use tokio::{
     sync::Mutex,
 };
 use tokio_tfo::TfoStream;
+use windows_sys::Win32::Networking::WinSock::htonl;
 use windows_sys::{
     core::PCSTR,
     Win32::{
         Foundation::{BOOL, ERROR_BUFFER_OVERFLOW, ERROR_NO_DATA, ERROR_SUCCESS},
         NetworkManagement::IpHelper::{
-            if_nametoindex,
-            GetAdaptersAddresses,
-            GAA_FLAG_SKIP_ANYCAST,
-            GAA_FLAG_SKIP_DNS_SERVER,
-            GAA_FLAG_SKIP_MULTICAST,
-            GAA_FLAG_SKIP_UNICAST,
-            IP_ADAPTER_ADDRESSES_LH,
+            if_nametoindex, GetAdaptersAddresses, GAA_FLAG_SKIP_ANYCAST, GAA_FLAG_SKIP_DNS_SERVER,
+            GAA_FLAG_SKIP_MULTICAST, GAA_FLAG_SKIP_UNICAST, IP_ADAPTER_ADDRESSES_LH,
         },
         Networking::WinSock::{
-            setsockopt,
-            WSAGetLastError,
-            WSAIoctl,
-            AF_UNSPEC,
-            IPPROTO_IP,
-            IPPROTO_IPV6,
-            IPPROTO_TCP,
-            IPV6_MTU_DISCOVER,
-            IPV6_UNICAST_IF,
-            IP_MTU_DISCOVER,
-            IP_PMTUDISC_DO,
-            IP_UNICAST_IF,
-            SIO_UDP_CONNRESET,
-            SOCKET,
-            SOCKET_ERROR,
+            setsockopt, WSAGetLastError, WSAIoctl, AF_UNSPEC, IPPROTO_IP, IPPROTO_IPV6, IPPROTO_TCP, IPV6_MTU_DISCOVER,
+            IPV6_UNICAST_IF, IP_MTU_DISCOVER, IP_PMTUDISC_DO, IP_UNICAST_IF, SIO_UDP_CONNRESET, SOCKET, SOCKET_ERROR,
             TCP_FASTOPEN,
         },
     },
@@ -66,9 +48,7 @@ const FALSE: BOOL = 0;
 use crate::net::{
     is_dual_stack_addr,
     sys::{set_common_sockopt_for_connect, socket_bind_dual_stack},
-    AcceptOpts,
-    AddrFamily,
-    ConnectOpts,
+    AcceptOpts, AddrFamily, ConnectOpts,
 };
 
 /// A `TcpStream` that supports TFO (TCP Fast Open)
@@ -334,20 +314,27 @@ async fn set_ip_unicast_if<S: AsRawSocket>(socket: &S, addr: &SocketAddr, iface:
     unsafe {
         // https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options
         let ret = match addr {
-            SocketAddr::V4(..) => setsockopt(
-                handle,
-                IPPROTO_IP as i32,
-                IP_UNICAST_IF as i32,
-                &if_index as *const _ as PCSTR,
-                mem::size_of_val(&if_index) as i32,
-            ),
-            SocketAddr::V6(..) => setsockopt(
-                handle,
-                IPPROTO_IPV6 as i32,
-                IPV6_UNICAST_IF as i32,
-                &if_index as *const _ as PCSTR,
-                mem::size_of_val(&if_index) as i32,
-            ),
+            SocketAddr::V4(..) => {
+                // Interface index is in network byte order for IPPROTO_IP.
+                let if_index = htonl(if_index);
+                setsockopt(
+                    handle,
+                    IPPROTO_IP as i32,
+                    IP_UNICAST_IF as i32,
+                    &if_index as *const _ as PCSTR,
+                    mem::size_of_val(&if_index) as i32,
+                )
+            }
+            SocketAddr::V6(..) => {
+                // Interface index is in host byte order for IPPROTO_IPV6.
+                setsockopt(
+                    handle,
+                    IPPROTO_IPV6 as i32,
+                    IPV6_UNICAST_IF as i32,
+                    &if_index as *const _ as PCSTR,
+                    mem::size_of_val(&if_index) as i32,
+                )
+            }
         };
 
         if ret == SOCKET_ERROR {