diff --git a/gate/kcp/session.go b/gate/kcp/session.go
index 9b96213f..3c56cf17 100644
--- a/gate/kcp/session.go
+++ b/gate/kcp/session.go
@@ -56,6 +56,15 @@ func init() {
 	}
 }
 
+const (
+	batchSize = 16
+)
+
+type batchConn interface {
+	WriteBatch(ms []ipv4.Message, flags int) (int, error)
+	ReadBatch(ms []ipv4.Message, flags int) (int, error)
+}
+
 type (
 	// UDPSession defines a KCP session implemented by UDP
 	UDPSession struct {
diff --git a/gate/kcp/udp_socket_linux.go b/gate/kcp/udp_socket_linux.go
index b1551d2e..856cc6eb 100644
--- a/gate/kcp/udp_socket_linux.go
+++ b/gate/kcp/udp_socket_linux.go
@@ -13,15 +13,6 @@ import (
 	"golang.org/x/net/ipv6"
 )
 
-const (
-	batchSize = 16
-)
-
-type batchConn interface {
-	WriteBatch(ms []ipv4.Message, flags int) (int, error)
-	ReadBatch(ms []ipv4.Message, flags int) (int, error)
-}
-
 // the read loop for a client session
 func (s *UDPSession) readLoop() {
 	// default version