diff --git a/src/pkg/syscall/ztypes_windows.go b/src/pkg/syscall/ztypes_windows.go
index 07f2b85f07..728812b843 100644
--- a/src/pkg/syscall/ztypes_windows.go
+++ b/src/pkg/syscall/ztypes_windows.go
@@ -359,6 +359,9 @@ const (
 
 	WSADESCRIPTION_LEN = 256
 	WSASYS_STATUS_LEN  = 128
+
+	IPV6_JOIN_GROUP  = 12
+	IPV6_LEAVE_GROUP = 13
 )
 
 type WSABuf struct {