diff --git a/ChangeLog b/ChangeLog
index c72917021e..519959a911 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,20 @@
 2017-06-09  Joseph Myers  <joseph@codesourcery.com>
 
+	[BZ #21561]
+	* posix/sys/wait.h (idtype_t): Change [__USE_XOPEN] condition to
+	[__USE_XOPEN_EXTENDED].
+	(id_t): Likewise.
+	(include of <bits/types/siginfo_t.h): Likewise.
+	(waitid): Likewise.
+	* sysdeps/unix/sysv/linux/bits/waitflags.h (WSTOPPED): Condition
+	on [__USE_XOPEN_EXTENDED || __USE_XOPEN2K8].
+	(WEXITED): Likewise.
+	(WCONTINUED): Likewise.
+	(WNOWAIT): Likewise.
+	* conform/Makefile (test-xfail-XPG4/stdlib.h/conform): Remove.
+	(test-xfail-XPG4/sys/wait.h/conform): Likewise.
+	(test-xfail-POSIX/sys/wait.h/conform): Likewise.
+
 	* sysdeps/unix/sysv/linux/nios2/localplt.data (__gtdf2): Mark
 	libc.so PLT entry optional.
 	(__gtsf2): Likewise.
diff --git a/conform/Makefile b/conform/Makefile
index ac6915357c..68f2e55298 100644
--- a/conform/Makefile
+++ b/conform/Makefile
@@ -162,12 +162,9 @@ test-xfail-XOPEN2K8/ndbm.h/conform = yes
 
 # Unsorted expected failures.
 test-xfail-XPG4/signal.h/conform = yes
-test-xfail-XPG4/stdlib.h/conform = yes
-test-xfail-XPG4/sys/wait.h/conform = yes
 test-xfail-XPG42/signal.h/conform = yes
 test-xfail-XPG42/sys/wait.h/conform = yes
 test-xfail-XPG42/ucontext.h/conform = yes
-test-xfail-POSIX/sys/wait.h/conform = yes
 test-xfail-UNIX98/signal.h/conform = yes
 test-xfail-UNIX98/sys/wait.h/conform = yes
 test-xfail-UNIX98/ucontext.h/conform = yes
diff --git a/posix/sys/wait.h b/posix/sys/wait.h
index 909979bc9d..f369a4b4a9 100644
--- a/posix/sys/wait.h
+++ b/posix/sys/wait.h
@@ -64,7 +64,7 @@ typedef __pid_t pid_t;
 #endif
 
 /* The following values are used by the `waitid' function.  */
-#if defined __USE_XOPEN || defined __USE_XOPEN2K8
+#if defined __USE_XOPEN_EXTENDED || defined __USE_XOPEN2K8
 typedef enum
 {
   P_ALL,		/* Wait for any child.  */
@@ -104,7 +104,7 @@ extern __pid_t wait (int *__stat_loc);
    __THROW.  */
 extern __pid_t waitpid (__pid_t __pid, int *__stat_loc, int __options);
 
-#if defined __USE_XOPEN || defined __USE_XOPEN2K8
+#if defined __USE_XOPEN_EXTENDED || defined __USE_XOPEN2K8
 # ifndef __id_t_defined
 typedef __id_t id_t;
 #  define __id_t_defined
diff --git a/sysdeps/unix/sysv/linux/bits/waitflags.h b/sysdeps/unix/sysv/linux/bits/waitflags.h
index 7dcb7b2f34..f0ea981f20 100644
--- a/sysdeps/unix/sysv/linux/bits/waitflags.h
+++ b/sysdeps/unix/sysv/linux/bits/waitflags.h
@@ -26,10 +26,12 @@
 #define	WUNTRACED	2	/* Report status of stopped children.  */
 
 /* Bits in the fourth argument to `waitid'.  */
-#define WSTOPPED	2	/* Report stopped child (same as WUNTRACED). */
-#define WEXITED		4	/* Report dead child.  */
-#define WCONTINUED	8	/* Report continued child.  */
-#define WNOWAIT		0x01000000 /* Don't reap, just poll status.  */
+#if defined __USE_XOPEN_EXTENDED || defined __USE_XOPEN2K8
+# define WSTOPPED	2	/* Report stopped child (same as WUNTRACED). */
+# define WEXITED	4	/* Report dead child.  */
+# define WCONTINUED	8	/* Report continued child.  */
+# define WNOWAIT	0x01000000 /* Don't reap, just poll status.  */
+#endif
 
 #define __WNOTHREAD     0x20000000 /* Don't wait on children of other threads
 				      in this group */