diff --git a/man/systemd-firstboot.xml b/man/systemd-firstboot.xml
index 81e62484fd..d6bfd855c1 100644
--- a/man/systemd-firstboot.xml
+++ b/man/systemd-firstboot.xml
@@ -98,6 +98,18 @@
         </para></listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term><option>--image=<replaceable>path</replaceable></option></term>
+        <listitem><para>Takes a path to a disk image file or block device node. If specified all operations
+        are applied to file system in the indicated disk image. This is similar to <option>--root=</option>
+        but operates on file systems stored in disk images or block devices. The disk image should either
+        contain just a file system or a set of file systems within a GPT partition table, following the
+        <ulink url="https://systemd.io/DISCOVERABLE_PARTITIONS">Discoverable Partitions
+        Specification</ulink>. For further information on supported disk images, see
+        <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
+        switch of the same name.</para></listitem>
+      </varlistentry>
+
       <varlistentry>
         <term><option>--locale=<replaceable>LOCALE</replaceable></option></term>
         <term><option>--locale-messages=<replaceable>LOCALE</replaceable></option></term>