diff --git a/docs/Getting Started/Debian/Debian Bullseye Root on ZFS.rst b/docs/Getting Started/Debian/Debian Bullseye Root on ZFS.rst
index f037e63..4fb7e36 100644
--- a/docs/Getting Started/Debian/Debian Bullseye Root on ZFS.rst	
+++ b/docs/Getting Started/Debian/Debian Bullseye Root on ZFS.rst	
@@ -528,6 +528,11 @@ Step 3: System Installation
    to limit the maximum space used. Otherwise, you can use a tmpfs (RAM
    filesystem) later.
 
+   **Note:** If you separate a directory required for booting (e.g. ``/etc``)
+   into its own dataset, you must add it to
+   ``ZFS_INITRD_ADDITIONAL_DATASETS`` in ``/etc/default/zfs``.  Datasets
+   with ``canmount=off`` (like ``rpool/usr`` above) do not matter for this.
+
 #. Mount a tmpfs at /run::
 
      mkdir /mnt/run
diff --git a/docs/Getting Started/Ubuntu/Ubuntu 22.04 Root on ZFS for Raspberry Pi.rst b/docs/Getting Started/Ubuntu/Ubuntu 22.04 Root on ZFS for Raspberry Pi.rst
index b6f1f1b..3d4d523 100644
--- a/docs/Getting Started/Ubuntu/Ubuntu 22.04 Root on ZFS for Raspberry Pi.rst	
+++ b/docs/Getting Started/Ubuntu/Ubuntu 22.04 Root on ZFS for Raspberry Pi.rst	
@@ -573,6 +573,11 @@ Step 3: System Installation
    to limit the maximum space used. Otherwise, you can use a tmpfs (RAM
    filesystem) later.
 
+   **Note:** If you separate a directory required for booting (e.g. ``/etc``)
+   into its own dataset, you must add it to
+   ``ZFS_INITRD_ADDITIONAL_DATASETS`` in ``/etc/default/zfs``.  Datasets
+   with ``canmount=off`` (like ``rpool/usr`` above) do not matter for this.
+
 #. Optional: Ignore synchronous requests:
 
    microSD cards are relatively slow.  If you want to increase performance
diff --git a/docs/Getting Started/Ubuntu/Ubuntu 22.04 Root on ZFS.rst b/docs/Getting Started/Ubuntu/Ubuntu 22.04 Root on ZFS.rst
index a17cea8..828256d 100644
--- a/docs/Getting Started/Ubuntu/Ubuntu 22.04 Root on ZFS.rst	
+++ b/docs/Getting Started/Ubuntu/Ubuntu 22.04 Root on ZFS.rst	
@@ -580,6 +580,11 @@ Step 3: System Installation
    to limit the maximum space used. Otherwise, you can use a tmpfs (RAM
    filesystem) later.
 
+   **Note:** If you separate a directory required for booting (e.g. ``/etc``)
+   into its own dataset, you must add it to
+   ``ZFS_INITRD_ADDITIONAL_DATASETS`` in ``/etc/default/zfs``.  Datasets
+   with ``canmount=off`` (like ``rpool/usr`` above) do not matter for this.
+
 #. Mount a tmpfs at /run::
 
      mkdir /mnt/run