diff --git a/qubes/devices.py b/qubes/devices.py
index 56b5bb524..f095f41d7 100644
--- a/qubes/devices.py
+++ b/qubes/devices.py
@@ -517,9 +517,12 @@ def serialize(self) -> bytes:
         properties += b' ' + interfaces_prop
 
         if self.parent_device is not None:
-            parent_ident = serialize_str(self.parent_device.ident)
-            parent_prop = (b'parent=' + parent_ident.encode('ascii'))
-            properties += b' ' + parent_prop
+            ident = serialize_str(self.parent_device.ident)
+            ident_prop = (b'parent_ident=' + ident.encode('ascii'))
+            properties += b' ' + ident_prop
+            devclass = serialize_str(self.parent_device.devclass)
+            devclass_prop = (b'parent_devclass=' + devclass.encode('ascii'))
+            properties += b' ' + devclass_prop
 
         data = b' '.join(
             f'_{prop}={serialize_str(value)}'.encode('ascii')
@@ -609,11 +612,14 @@ def _deserialize(
             for i in range(0, len(interfaces), 7)]
         properties['interfaces'] = interfaces
 
-        if 'parent' in properties:
+        if 'parent_ident' in properties:
             properties['parent'] = Device(
                 backend_domain=expected_backend_domain,
-                ident=properties['parent']
+                ident=properties['parent_ident'],
+                devclass=properties['parent_devclass'],
             )
+            del properties['parent_ident']
+            del properties['parent_devclass']
 
         return cls(**properties)
 
diff --git a/qubes/ext/block.py b/qubes/ext/block.py
index 635f979cd..19b4fb9ce 100644
--- a/qubes/ext/block.py
+++ b/qubes/ext/block.py
@@ -422,12 +422,14 @@ def on_device_pre_attached_block(self, vm, event, device, options):
                     )
             elif option == 'parent_identity':
                 identity = value
-                if device.parent.self_identity != identity:
+                p = device.parent_device
+                parent_info = p.backend_domain.devices[p.devclass][p.ident]
+                if parent_info.self_identity != identity:
                     print("Unrecognized parent identity, skipping attachment of"
                           f" {device}", file=sys.stderr)
                     raise qubes.devices.UnrecognizedDevice(
                         f"Parent device of {device} presents identity that"
-                        f" {device.parent.self_identity} "
+                        f" {parent_info.self_identity} "
                         f"does not match expected {identity}"
                     )
             else: