diff --git a/xye/src/gen.cpp b/xye/src/gen.cpp
index 3515972..51f64f3 100644
--- a/xye/src/gen.cpp
+++ b/xye/src/gen.cpp
@@ -15,6 +15,7 @@ Permission is granted to anyone to use this software for any purpose, including
 
 */
 
+#include <unistd.h>
 
 #include "gen.h"
 #include "vxsdl.h"