diff --git a/ChangeLog b/ChangeLog
index dd35b6c05b..5c40ad8035 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2016-04-25  Joseph Myers  <joseph@codesourcery.com>
+
+	[BZ #19989]
+	* libio/stdio.h (cuserid): Do not declare if
+	[__USE_XOPEN2K && !__USE_GNU].
+	* conform/Makefile (test-xfail-XOPEN2K8/stdio.h/conform): Remove
+	variable.
+
 2016-04-25  Paul E. Murphy  <murphyp@linux.vnet.ibm.com>
 
 	* sysdeps/powerpc/powerpc64/multiarch/Makefile:
diff --git a/conform/Makefile b/conform/Makefile
index 0b5514c861..e3baec7c9f 100644
--- a/conform/Makefile
+++ b/conform/Makefile
@@ -226,7 +226,6 @@ test-xfail-POSIX2008/signal.h/conform = yes
 test-xfail-POSIX2008/sys/socket.h/conform = yes
 test-xfail-POSIX2008/sys/wait.h/conform = yes
 test-xfail-XOPEN2K8/signal.h/conform = yes
-test-xfail-XOPEN2K8/stdio.h/conform = yes
 test-xfail-XOPEN2K8/sys/wait.h/conform = yes
 
 conformtest-cc-flags = -I../include $(+sysdep-includes) $(sysincludes) -I..
diff --git a/libio/stdio.h b/libio/stdio.h
index d8d7fa0611..4b66530460 100644
--- a/libio/stdio.h
+++ b/libio/stdio.h
@@ -885,7 +885,7 @@ extern char *ctermid (char *__s) __THROW;
 #endif /* Use POSIX.  */
 
 
-#ifdef __USE_XOPEN
+#if (defined __USE_XOPEN && !defined __USE_XOPEN2K) || defined __USE_GNU
 /* Return the name of the current user.  */
 extern char *cuserid (char *__s);
 #endif /* Use X/Open, but not issue 6.  */