diff --git a/netbox/virtualization/migrations/0041_convert_disk_size.py b/netbox/virtualization/migrations/0041_convert_disk_size.py
index 3e6fa1b5e..755fec27e 100644
--- a/netbox/virtualization/migrations/0041_convert_disk_size.py
+++ b/netbox/virtualization/migrations/0041_convert_disk_size.py
@@ -13,6 +13,7 @@ def convert_disk_size(apps, schema_editor):
     VirtualMachine = apps.get_model('virtualization', 'VirtualMachine')
     vms = VirtualMachine.objects.filter(id__in=id_list)
     for vm in vms:
+        vm.disk = self.virtualdisks.aggregate(Sum('size', default=0))['size__sum']
         vm.save()