diff --git a/demo_test/vendor/golang.org/x/sys/unix/pagesize_unix.go b/demo_test/vendor/golang.org/x/sys/unix/pagesize_unix.go
new file mode 100644
index 0000000..bc2f362
--- /dev/null
+++ b/demo_test/vendor/golang.org/x/sys/unix/pagesize_unix.go
@@ -0,0 +1,15 @@
+// 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 aix darwin dragonfly freebsd linux netbsd openbsd solaris
+
+// For Unix, get the pagesize from the runtime.
+
+package unix
+
+import "syscall"
+
+func Getpagesize() int {
+	return syscall.Getpagesize()
+}