diff --git a/unum/vendor/golang.org/x/net/ipv4/control_windows.go b/unum/vendor/golang.org/x/net/ipv4/control_windows.go
new file mode 100644
index 0000000..ce55c66
--- /dev/null
+++ b/unum/vendor/golang.org/x/net/ipv4/control_windows.go
@@ -0,0 +1,16 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ipv4
+
+import (
+	"syscall"
+
+	"golang.org/x/net/internal/socket"
+)
+
+func setControlMessage(c *socket.Conn, opt *rawOpt, cf ControlFlags, on bool) error {
+	// TODO(mikio): implement this
+	return syscall.EWINDOWS
+}