--- a/src/universe.hpp
+++ b/src/universe.hpp
@@ -5,6 +5,10 @@
 #include "keeper.hpp"
 #include "lanesconf.h"
 #include "threading.hpp"
+
+#ifdef PLATFORM_LINUX
+#include <unistd.h>
+#endif
 #include "tracker.hpp"
 #include "uniquekey.hpp"