diff --git a/ChangeLog b/ChangeLog
index 77751d628d..e6fe2aa1ad 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2018-03-27  Samuel Thibault  <samuel.thibault@ens-lyon.org>
+
+	* sysdeps/mach/hurd/bits/posix_opt.h (_POSIX_MEMLOCK): Define.
+
 2018-03-27  Andreas Schwab  <schwab@suse.de>
 
 	[BZ #23005]
diff --git a/sysdeps/mach/hurd/bits/posix_opt.h b/sysdeps/mach/hurd/bits/posix_opt.h
index 828d7ffc77..d42c010c20 100644
--- a/sysdeps/mach/hurd/bits/posix_opt.h
+++ b/sysdeps/mach/hurd/bits/posix_opt.h
@@ -42,8 +42,8 @@
 /* Mapping of files to memory is supported.  */
 #define	_POSIX_MAPPED_FILES	200809L
 
-/* Locking of all memory could be supported in future.  */
-#define	_POSIX_MEMLOCK	0
+/* Locking of all memory is supported.  */
+#define	_POSIX_MEMLOCK	200809L
 
 /* Locking of ranges of memory is supported.  */
 #define	_POSIX_MEMLOCK_RANGE	200809L