diff --git a/man/machine-id.xml b/man/machine-id.xml
index b40e26bbab..ec1ab64dec 100644
--- a/man/machine-id.xml
+++ b/man/machine-id.xml
@@ -147,7 +147,8 @@
     </orderedlist>
 
     <para>If according to the above rules a first boot is detected, units with
-    <varname>ConditionFirstBoot=yes</varname> will be run.</para>
+    <varname>ConditionFirstBoot=yes</varname> will be run and <command>systemd</command> will perform
+    additional initialization steps, in particular presetting units.</para>
   </refsect1>
 
   <refsect1>
diff --git a/man/systemd.preset.xml b/man/systemd.preset.xml
index 9e6db28536..ab730d2cc2 100644
--- a/man/systemd.preset.xml
+++ b/man/systemd.preset.xml
@@ -47,12 +47,16 @@
     units, but rather centralize them in a distribution or spin default policy, which can be amended by
     administrator policy, see below.</para>
 
-    <para>If no preset files exist, <command>systemctl
-    preset</command> will enable all units that are installed by
-    default. If this is not desired and all units shall rather be
-    disabled, it is necessary to ship a preset file with a single,
-    catchall "<filename>disable *</filename>" line. (See example 1,
-    below.)</para>
+    <para>If no preset files exist, preset operations will enable all units that are installed by default. If
+    this is not desired and all units shall rather be disabled, it is necessary to ship a preset file with a
+    single, catchall "<filename>disable *</filename>" line. (See example 1, below.)</para>
+
+    <para>When the machine is booted for the first time,
+    <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry> will
+    enable/disable all units according to preset policy, similarly to <command>systemctl
+    preset-all</command>. Also see "First Boot Semantics" in
+    <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+    </para>
   </refsect1>
 
   <refsect1>
diff --git a/man/systemd.xml b/man/systemd.xml
index f4213e2ee8..1a68301d50 100644
--- a/man/systemd.xml
+++ b/man/systemd.xml
@@ -188,8 +188,13 @@
     <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>
     for details about these target units.</para>
 
-    <para>systemd only keeps a minimal set of units loaded into memory. Specifically, the only units that are kept
-    loaded into memory are those for which at least one of the following conditions is true:</para>
+    <para>On first boot, <command>systemd</command> will enable or disable units according to preset policy.
+    See <citerefentry><refentrytitle>systemd.preset</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+    and "First Boot Semantics" in
+    <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
+
+    <para>systemd only keeps a minimal set of units loaded into memory. Specifically, the only units that are
+    kept loaded into memory are those for which at least one of the following conditions is true:</para>
 
     <orderedlist>
       <listitem><para>It is in an active, activating, deactivating or failed state (i.e. in any unit state except for <literal>inactive</literal>)</para></listitem>