diff --git a/nixos/doc/manual/from_md/installation/building-nixos.chapter.xml b/nixos/doc/manual/from_md/installation/building-nixos.chapter.xml
index e7a76a6d715d..ea2d01bebcc2 100644
--- a/nixos/doc/manual/from_md/installation/building-nixos.chapter.xml
+++ b/nixos/doc/manual/from_md/installation/building-nixos.chapter.xml
@@ -33,9 +33,14 @@
   </para>
   <section xml:id="sec-building-image-instructions">
     <title>Practical Instructions</title>
+    <para>
+      To build an ISO image for the channel
+      <literal>nixos-unstable</literal>:
+    </para>
     <programlisting>
 $ git clone https://github.com/NixOS/nixpkgs.git
 $ cd nixpkgs/nixos
+$ git switch nixos-unstable
 $ nix-build -A config.system.build.isoImage -I nixos-config=modules/installer/cd-dvd/installation-cd-minimal.nix default.nix
 </programlisting>
     <para>
diff --git a/nixos/doc/manual/installation/building-nixos.chapter.md b/nixos/doc/manual/installation/building-nixos.chapter.md
index 27d7e1d38553..17da261fbdaa 100644
--- a/nixos/doc/manual/installation/building-nixos.chapter.md
+++ b/nixos/doc/manual/installation/building-nixos.chapter.md
@@ -18,9 +18,12 @@ enforced values with `mkForce`.
 
 ## Practical Instructions {#sec-building-image-instructions}
 
+To build an ISO image for the channel `nixos-unstable`:
+
 ```ShellSession
 $ git clone https://github.com/NixOS/nixpkgs.git
 $ cd nixpkgs/nixos
+$ git switch nixos-unstable
 $ nix-build -A config.system.build.isoImage -I nixos-config=modules/installer/cd-dvd/installation-cd-minimal.nix default.nix
 ```