diff --git a/master/ethernet.h b/master/ethernet.h
index f14a8e87..109349d7 100644
--- a/master/ethernet.h
+++ b/master/ethernet.h
@@ -39,6 +39,7 @@
 
 #include <linux/list.h>
 #include <linux/netdevice.h>
+#include <linux/semaphore.h>
 
 #include "globals.h"
 #include "slave.h"