diff --git a/src/sql/mdbsql.c b/src/sql/mdbsql.c
index c92615b..4ffeb59 100644
--- a/src/sql/mdbsql.c
+++ b/src/sql/mdbsql.c
@@ -18,7 +18,7 @@
 
 #include <stdarg.h>
 #ifndef _XOPEN_SOURCE
-#define _XOPEN_SOURCE
+#define _XOPEN_SOURCE 600
 #endif
 #include "mdbsql.h"