diff --git a/src/lib/drivers/pn532_uart.c b/src/lib/drivers/pn532_uart.c
index 86164bc..d22aae5 100644
--- a/src/lib/drivers/pn532_uart.c
+++ b/src/lib/drivers/pn532_uart.c
@@ -20,7 +20,7 @@
  * @file pn532_uart.c
  * @brief
  */
-#define _XOPEN_SOURCE 500
+#define _XOPEN_SOURCE 600
 #include <stdio.h>
 #include <string.h>