diff --git a/windows/syscall_windows.go b/windows/syscall_windows.go
index 636e5de..be3ec2b 100644
--- a/windows/syscall_windows.go
+++ b/windows/syscall_windows.go
@@ -861,6 +861,7 @@
 //sys	GetAdaptersAddresses(family uint32, flags uint32, reserved uintptr, adapterAddresses *IpAdapterAddresses, sizePointer *uint32) (errcode error) = iphlpapi.GetAdaptersAddresses
 //sys	GetACP() (acp uint32) = kernel32.GetACP
 //sys	MultiByteToWideChar(codePage uint32, dwFlags uint32, str *byte, nstr int32, wchar *uint16, nwchar int32) (nwrite int32, err error) = kernel32.MultiByteToWideChar
+//sys	getBestInterfaceEx(sockaddr unsafe.Pointer, pdwBestIfIndex *uint32) (errcode error) = iphlpapi.GetBestInterfaceEx
 
 // For testing: clients can set this flag to force
 // creation of IPv6 sockets to return EAFNOSUPPORT.
@@ -1045,6 +1046,14 @@
 	return connect(fd, ptr, n)
 }
 
+func GetBestInterfaceEx(sa Sockaddr, pdwBestIfIndex *uint32) (err error) {
+	ptr, _, err := sa.sockaddr()
+	if err != nil {
+		return err
+	}
+	return getBestInterfaceEx(ptr, pdwBestIfIndex)
+}
+
 func Getsockname(fd Handle) (sa Sockaddr, err error) {
 	var rsa RawSockaddrAny
 	l := int32(unsafe.Sizeof(rsa))
diff --git a/windows/zsyscall_windows.go b/windows/zsyscall_windows.go
index 68f52c1..678262c 100644
--- a/windows/zsyscall_windows.go
+++ b/windows/zsyscall_windows.go
@@ -177,6 +177,7 @@
 	procDnsRecordListFree                                    = moddnsapi.NewProc("DnsRecordListFree")
 	procGetAdaptersAddresses                                 = modiphlpapi.NewProc("GetAdaptersAddresses")
 	procGetAdaptersInfo                                      = modiphlpapi.NewProc("GetAdaptersInfo")
+	procGetBestInterfaceEx                                   = modiphlpapi.NewProc("GetBestInterfaceEx")
 	procGetIfEntry                                           = modiphlpapi.NewProc("GetIfEntry")
 	procAssignProcessToJobObject                             = modkernel32.NewProc("AssignProcessToJobObject")
 	procCancelIo                                             = modkernel32.NewProc("CancelIo")
@@ -1539,6 +1540,14 @@
 	return
 }
 
+func getBestInterfaceEx(sockaddr unsafe.Pointer, pdwBestIfIndex *uint32) (errcode error) {
+	r0, _, _ := syscall.Syscall(procGetBestInterfaceEx.Addr(), 2, uintptr(sockaddr), uintptr(unsafe.Pointer(pdwBestIfIndex)), 0)
+	if r0 != 0 {
+		errcode = syscall.Errno(r0)
+	}
+	return
+}
+
 func GetIfEntry(pIfRow *MibIfRow) (errcode error) {
 	r0, _, _ := syscall.Syscall(procGetIfEntry.Addr(), 1, uintptr(unsafe.Pointer(pIfRow)), 0, 0)
 	if r0 != 0 {