diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 821722ae58a..86b3796b043 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -118,7 +118,7 @@ struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *old
 {
 	if (!(flags & CLONE_NEWPID))
 		return get_pid_ns(old_ns);
-	if (flags & CLONE_THREAD)
+	if (flags & (CLONE_THREAD|CLONE_PARENT))
 		return ERR_PTR(-EINVAL);
 	return create_pid_namespace(old_ns);
 }