diff --git a/man/udev.xml b/man/udev.xml
index 09254f818e..9b97ee63d9 100644
--- a/man/udev.xml
+++ b/man/udev.xml
@@ -465,6 +465,10 @@
             that is enforced on <filename>systemd-udevd.service</filename>.</para>
             <para>Please also note that <literal>:=</literal> and <literal>=</literal> are clearing
             both, program and builtin commands.</para>
+            <para>In order to activate long-running processes from udev rules, provide a service unit, and
+            pull it in from a udev device using the <varname>SYSTEMD_WANTS</varname> device property. See
+            <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+            for details.</para>
           </listitem>
         </varlistentry>