diff --git a/nixos/doc/manual/configuration/x-windows.xml b/nixos/doc/manual/configuration/x-windows.xml
index 7cdc5196e0d..f6f659b02af 100644
--- a/nixos/doc/manual/configuration/x-windows.xml
+++ b/nixos/doc/manual/configuration/x-windows.xml
@@ -279,6 +279,12 @@ xkb_symbols "media"
 <programlisting>
 <xref linkend="opt-services.xserver.displayManager.sessionCommands"/> = "setxkbmap -keycodes media";
 </programlisting>
+  <para>
+    If you are manually starting the X server, you should set the argument
+    <literal>-xkbdir /etc/X11/xkb</literal>, otherwise X won't find your layout files.
+    For example with <command>xinit</command> run
+    <screen><prompt>$ </prompt>xinit -- -xkbdir /etc/X11/xkb</screen>
+  </para>
   <para>
    To learn how to write layouts take a look at the XKB
   <link xlink:href="https://www.x.org/releases/current/doc/xorg-docs/input/XKB-Enhancing.html#Defining_New_Layouts">