diff --git a/unum/vendor/golang.org/x/net/internal/socket/error_unix.go b/unum/vendor/golang.org/x/net/internal/socket/error_unix.go
new file mode 100644
index 0000000..93dff91
--- /dev/null
+++ b/unum/vendor/golang.org/x/net/internal/socket/error_unix.go
@@ -0,0 +1,31 @@
+// 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 darwin dragonfly freebsd linux netbsd openbsd solaris
+
+package socket
+
+import "syscall"
+
+var (
+	errEAGAIN error = syscall.EAGAIN
+	errEINVAL error = syscall.EINVAL
+	errENOENT error = syscall.ENOENT
+)
+
+// errnoErr returns common boxed Errno values, to prevent allocations
+// at runtime.
+func errnoErr(errno syscall.Errno) error {
+	switch errno {
+	case 0:
+		return nil
+	case syscall.EAGAIN:
+		return errEAGAIN
+	case syscall.EINVAL:
+		return errEINVAL
+	case syscall.ENOENT:
+		return errENOENT
+	}
+	return errno
+}