--- lib/Display.cc.orig	Tue Apr 25 16:22:31 2017
+++ lib/Display.cc	Tue Apr 25 16:22:38 2017
@@ -31,6 +31,7 @@
 #include <assert.h>
 #include <fcntl.h>
 #include <stdio.h>
+#include <stdlib.h>
 
 
 namespace bt {