diff --git a/serial/serial_darwin.go b/serial/serial_darwin.go
new file mode 100644
index 0000000..7e6f0ce
--- /dev/null
+++ b/serial/serial_darwin.go
@@ -0,0 +1,14 @@
+// Copyright 2018 The Fuchsia 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 serial
+
+import (
+	"errors"
+	"io"
+)
+
+func open(name string, baudRate int, timeoutSecs int) (io.ReadWriteCloser, error) {
+	return nil, errors.New("not supported")
+}
diff --git a/serial/serial_linux.go b/serial/serial_linux.go
index bb5ddc8..a93db9e 100644
--- a/serial/serial_linux.go
+++ b/serial/serial_linux.go
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// +build linux
-
 package serial
 
 import (