diff --git a/disko/disko-config.nix b/disko/disko-config.nix
index 223bf032..d90079a0 100644
--- a/disko/disko-config.nix
+++ b/disko/disko-config.nix
@@ -60,7 +60,7 @@
           # error messages:
           #   Volume group "lvm-chaos" has insufficient free space (51195 extents): 51200 required.
           #   Size is not a multiple of 512. Try using 40057405440 or 40057405952.
-          raw.size =
+          ceph.size =
             let
               # convert GiB to bytes
               rootSizeMiB = rootSize * 1024 * 1024 * 1024;
@@ -70,6 +70,7 @@
               bootOther = "-512-20";
             in
             "$((($(lsblk /dev/sda --noheadings --nodeps --output SIZE --bytes)-${toString rootSizeMiB})${roundToMiB}${bootOther}))MiB";
+          # TODO: ask astro how to format this
           zfs = {
             size = "${toString rootSize}GiB";
             content = {