diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
index 03f8b1b655..e22acb17f2 100644
--- a/docs/about/deprecated.rst
+++ b/docs/about/deprecated.rst
@@ -258,6 +258,14 @@ dropping the ``cheetah`` OMAP1 board, because we don't have any
 test images for it and don't know of anybody who does; the ``sx1``
 and ``sx1-v1`` OMAP1 machines remain supported for now.
 
+PPC 405 ``ref405ep`` machine (since 9.1)
+''''''''''''''''''''''''''''''''''''''''
+
+The ``ref405ep`` machine and PPC 405 CPU have no known users, firmware
+images are not available, OpenWRT dropped support in 2019, U-Boot in
+2017, Linux also is dropping support in 2024. It is time to let go of
+this ancient hardware and focus on newer CPUs and platforms.
+
 Backend options
 ---------------
 
diff --git a/hw/ppc/ppc405_boards.c b/hw/ppc/ppc405_boards.c
index 4092ebc1ab..c44e7ed162 100644
--- a/hw/ppc/ppc405_boards.c
+++ b/hw/ppc/ppc405_boards.c
@@ -350,6 +350,7 @@ static void ppc405_machine_class_init(ObjectClass *oc, void *data)
     mc->init = ppc405_init;
     mc->default_ram_size = 128 * MiB;
     mc->default_ram_id = "ppc405.ram";
+    mc->deprecation_reason = "machine is old and unmaintained";
 }
 
 static const TypeInfo ppc405_machine_type = {