diff --git a/disk/config.toml b/disk/config.toml
index ae04f51..afe62bf 100644
--- a/disk/config.toml
+++ b/disk/config.toml
@@ -1,8 +1,8 @@
 # bootc-image-builder's config for the disk image (task build-disk-image).
 # No user: the image has none, so plasma-setup (Aurora's, enabled by
-# default) creates the first one at first boot. Root's minimum size only;
-# a qcow2 is sparse, so the download is the size of what's written, not 64
+# default) creates the first one at first boot. Only the disk's minimum
+# size (customizations.filesystem isn't supported for disk images); a
+# qcow2 is sparse, so the download is the size of what's written, not 64
 # GiB.
-[[customizations.filesystem]]
-mountpoint = "/"
+[customizations.disk]
 minsize = "64 GiB"