apple
diff --git a/include/u.h b/include/u.h
index 8e889e6..1489ebd 100644
--- a/include/u.h
+++ b/include/u.h
@@ -10,8 +10,10 @@
#define _BSD_SOURCE 1
#define _NETBSD_SOURCE 1 /* NetBSD */
#define _SVID_SOURCE 1
-#define _XOPEN_SOURCE 1000
-#define _XOPEN_SOURCE_EXTENDED 1
+#ifndef __APPLE__
+# define _XOPEN_SOURCE 1000
+# define _XOPEN_SOURCE_EXTENDED 1
+#endif
#define _LARGEFILE64_SOURCE 1
#define _FILE_OFFSET_BITS 64
@@ -78,6 +80,7 @@
# endif
# undef _ANSI_SOURCE
# undef _POSIX_C_SOURCE
+# undef _XOPEN_SOURCE
# if !defined(NSIG)
# define NSIG 32
# endif