--- src/celengine/frametree.h.orig	2014-04-26 16:08:47.217900392 +0200
+++ src/celengine/frametree.h	2014-04-26 16:09:09.601899991 +0200
@@ -13,6 +13,7 @@
 #ifndef _CELENGINE_FRAMETREE_H_
 #define _CELENGINE_FRAMETREE_H_
 
+#include <unistd.h>
 #include <vector>
 
 class Star;
