diff --git a/unum/vendor/golang.org/x/net/internal/socket/sys_bsdvar.go b/unum/vendor/golang.org/x/net/internal/socket/sys_bsdvar.go
new file mode 100644
index 0000000..f723fa3
--- /dev/null
+++ b/unum/vendor/golang.org/x/net/internal/socket/sys_bsdvar.go
@@ -0,0 +1,14 @@
+// Copyright 2017 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.
+
+// +build freebsd netbsd openbsd
+
+package socket
+
+import "unsafe"
+
+func probeProtocolStack() int {
+	var p uintptr
+	return int(unsafe.Sizeof(p))
+}