diff --git a/build/lua_5.2.1.h b/build/lua_5.2.1.h
index 2849a678..c51afd71 100644
--- a/build/lua_5.2.1.h
+++ b/build/lua_5.2.1.h
@@ -8,10 +8,11 @@
 #ifndef lconfig_h
 #define lconfig_h
 
+#define _XOPEN_SOURCE 600  // Makes it compile under linux
+
 #include <limits.h>
 #include <stddef.h>
 
-
 /*
 ** ==================================================================
 ** Search for "@@" to find all configurable definitions.