diff --git a/ChangeLog b/ChangeLog
index 23c900dcf7..eb604b854b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2014-08-28  Samuel Thibault  <samuel.thibault@ens-lyon.org>
+
+	* sysdeps/mach/hurd/fork.c (__fork): Lock SS->lock around
+	__proc_dostop call.
+
 2014-08-27  Mark Wielaard  <mjw@redhat.com>
 
 	[BZ #17319]
diff --git a/sysdeps/mach/hurd/fork.c b/sysdeps/mach/hurd/fork.c
index 60c34c7620..51bc2c0753 100644
--- a/sysdeps/mach/hurd/fork.c
+++ b/sysdeps/mach/hurd/fork.c
@@ -129,9 +129,13 @@ __fork (void)
       ports_locked = 1;
 
 
+      /* Keep our SS locked while stopping other threads, so they don't get a
+         chance to have it locked in the copied space.  */
+      __spin_lock (&ss->lock);
       /* Stop all other threads while copying the address space,
 	 so nothing changes.  */
       err = __proc_dostop (_hurd_ports[INIT_PORT_PROC].port, ss->thread);
+      __spin_unlock (&ss->lock);
       if (!err)
 	{
 	  stopped = 1;