diff --git a/guix/installer.scm b/guix/installer.scm
index 4032687..46766a1 100644
--- a/guix/installer.scm
+++ b/guix/installer.scm
@@ -1,6 +1,8 @@
 ;;; Copyright © 2019 Alex Griffin <a@ajgrf.com>
 ;;; Copyright © 2019 Pierre Neidhardt <mail@ambrevar.xyz>
-;;; Copyright © 2019 David Wilson <david@daviwil.com>
+;;; Copyright © 2019,2024 David Wilson <david@daviwil.com>
+;;; Copyright © 2022 Jonathan Brielmaier <jonathan.brielmaier@web.de>
+;;; Copyright © 2024 Hilton Chain <hako@ultrarare.space>
 ;;;
 ;;; This program is free software: you can redistribute it and/or modify
 ;;; it under the terms of the GNU General Public License as published by
@@ -19,9 +21,8 @@
 ;; $ guix system image -t iso9660 installer.scm
 
 (define-module (nongnu system install)
-  #:use-module (gnu services)
-  #:use-module (gnu system)
-  #:use-module (gnu system install)
+  #:use-module (guix)
+  #:use-module (guix channels)
   #:use-module (gnu packages version-control)
   #:use-module (gnu packages vim)
   #:use-module (gnu packages curl)
@@ -29,10 +30,33 @@
   #:use-module (gnu packages linux)
   #:use-module (gnu packages mtools)
   #:use-module (gnu packages package-management)
+  #:use-module (gnu services)
+  #:use-module (gnu services base)
+  #:use-module (gnu system)
+  #:use-module (gnu system install)
   #:use-module (nongnu packages linux)
-  #:use-module (guix)
   #:export (installation-os-nonfree))
 
+;; https://substitutes.nonguix.org/signing-key.pub
+(define %signing-key
+  (plain-file "nonguix.pub" "\
+(public-key
+ (ecc
+  (curve Ed25519)
+  (q #C1FD53E5D4CE971933EC50C9F307AE2171A2D3B52C804642A7A35F84F3A4EA98#)))"))
+
+(define %channels
+  (cons* (channel
+          (name 'nonguix)
+          (url "https://gitlab.com/nonguix/nonguix")
+          ;; Enable signature verification:
+          (introduction
+           (make-channel-introduction
+            "897c1a470da759236cc11798f4e0a5f7d4d59fbc"
+            (openpgp-fingerprint
+             "2A39 3FFF 68F4 EF7A 3D29  12AF 6F51 20A0 22FB B2D5"))))
+         %default-channels))
+
 (define installation-os-nonfree
   (operating-system
     (inherit installation-os)
@@ -49,7 +73,19 @@
       ;; Include the channel file so that it can be used during installation
       (simple-service 'channel-file etc-service-type
                       (list `("channels.scm" ,(local-file "channels.scm"))))
-      (operating-system-user-services installation-os)))
+
+      (modify-services (operating-system-user-services installation-os)
+        (guix-service-type
+         config => (guix-configuration
+                    (inherit config)
+                    (guix (guix-for-channels %channels))
+                    (authorized-keys
+                     (cons* %signing-key
+                            %default-authorized-guix-keys))
+                    (substitute-urls
+                     `(,@%default-substitute-urls
+                       "https://substitutes.nonguix.org"))
+                    (channels %channels))))))
 
     ;; Add some extra packages useful for the installation process
     (packages