diff --git a/sys/include/fd.h b/sys/include/fd.h
index 9b5fa98bec..95da6eaa36 100644
--- a/sys/include/fd.h
+++ b/sys/include/fd.h
@@ -23,6 +23,7 @@
 #define FD_H
 #include <stdlib.h>
 #include <sys/types.h>
+#include "cpu.h"
 
 /**
  * File descriptor table.