diff --git a/src/middlewared/middlewared/plugins/device.py b/src/middlewared/middlewared/plugins/device.py
index a2805b646e6e9..46469c4faabdc 100644
--- a/src/middlewared/middlewared/plugins/device.py
+++ b/src/middlewared/middlewared/plugins/device.py
@@ -33,7 +33,7 @@ class Config:
                 Str('pci_slot', required=True),
                 Str('domain', required=True),
                 Str('bus', required=True),
-                Str('slot', True),
+                Str('slot', required=True),
             ),
             Str('description', required=True),
             List('devices', items=[Dict(