diff --git a/audio-linux.go b/audio-linux.go
index 7ba7951..ca46de1 100644
--- a/audio-linux.go
+++ b/audio-linux.go
@@ -1,3 +1,5 @@
+// +build linux
+
 package main
 
 import (
diff --git a/serial-linux.go b/serial-linux.go
index 1a7d299..bbf5fe3 100644
--- a/serial-linux.go
+++ b/serial-linux.go
@@ -1,3 +1,5 @@
+// +build linux
+
 package main
 
 import (