Index: src/OFDate.m
==================================================================
--- src/OFDate.m
+++ src/OFDate.m
@@ -12,11 +12,11 @@
  * Public License, either version 2 or 3, which can be found in the file
  * LICENSE.GPLv2 or LICENSE.GPLv3 respectively included in the packaging of this
  * file.
  */
 
-#define _POSIX_SOURCE
+#define _XOPEN_SOURCE 500
 
 #include "config.h"
 
 #include <stdint.h>
 #include <limits.h>

Index: src/OFFile.m
==================================================================
--- src/OFFile.m
+++ src/OFFile.m
@@ -12,11 +12,11 @@
  * Public License, either version 2 or 3, which can be found in the file
  * LICENSE.GPLv2 or LICENSE.GPLv3 respectively included in the packaging of this
  * file.
  */
 
-#define _POSIX_C_SOURCE 200112L
+#define _XOPEN_SOURCE 500
 
 #include "config.h"
 
 #define __NO_EXT_QNX