--- src/args.c.orig	2019-10-20 13:04:21.000000000 +0200
+++ src/args.c	2019-10-20 13:04:26.000000000 +0200
@@ -67,7 +67,7 @@
  * here as well. */
 
 #ifndef _XOPEN_SOURCE
-#define _XOPEN_SOURCE 500    /* strdup(3) */
+#define _XOPEN_SOURCE 600    /* strdup(3) */
 #endif
 
 #include <ctype.h>