diff --git a/nongnu/system/build-image.scm b/nongnu/system/build-image.scm
index 541ea0b..e18c8da 100644
--- a/nongnu/system/build-image.scm
+++ b/nongnu/system/build-image.scm
@@ -1,7 +1,9 @@
+
 #!/usr/bin/env -S guile \\
 -e build-image -s
-!# ;; Guile uses a meta switch '\' which env requires escaping to passthru.
-;; See: https://pingus.seul.org/~grumbel/tmp/guile-1.6.0/guile_10.html#SEC27
+!#
+; Guile uses a meta switch '\' which env requires escaping to passthru.
+; See: https://pingus.seul.org/~grumbel/tmp/guile-1.6.0/guile_10.html#SEC27
 
 ;;; Copyright © 2021 Kyle Cassidy <123_kbc@pm.me>
 ;;;
@@ -21,6 +23,8 @@
 ;; Generate a bootable image with:
 ;; $ chmod +x build-image.scm && ./build-image.scm
 
+(use-modules (ice-9 pretty-print))
+
 ; Searches through Scheme file for 'define and 'define* expressions
 ; such as (define <name> ... ) or (define (<name> ...) ...)
 (define (search-for-define scheme-file define-name)
@@ -37,47 +41,41 @@
                exp)
               (#t (next (read port))))))))
 
-; Writes channel-list to a tmpfile
-; 'use-module is assumed to be needed, does not do anything if not used. TODO: remove assumption.
-; TODO: get mkstemp! to work (result of using it was a blank file)
-(define (make-tmp-channel channel-list)
-  (let loop ((tmpath (string-append "/tmp/guix-channel"
-                                    (number->string (random 1000000)))))
-    (cond ((file-exists? tmpath)
-           (loop (string-append "/tmp/guix-channel"
-                                (number->string (random 1000000)))))
-          (#t (call-with-output-file tmpath
-                (lambda (port)
-                  (write '(use-modules (guix ci)) port)
-                  (write channel-list port)))
-            tmpath))))
+; Writes channel-list to a temp file
+(define (make-temp-channel channel-list)
+  (let ((port (mkstemp! (string-copy "/tmp/guix-channel-XXXXXX") "a")))
+    (map (lambda (_) (pretty-print _ port))
+      channel-list)
+    (force-output port)
+    (port-filename port)))
 
 ; Main function called when run at command line.
 ;   Parses "nongnu/system/install.scm" for channel definition
 ;     (current-filename) used to locate in same dir as this file
-;   Creates tmpfile containing channel definition
-;   Performs a guix pull using tmpfile as channel file
-;   Deletes tmpfile
+;   Creates a temp file containing channel definition
+;   Performs a guix pull using temp file as channel file
+;   Deletes temp file
 ;   Builds image (currently iso only)
 ;     supports "--uncompressed" command line argument
 ;   If "--roll-back" is used as an argument, reverts guix pull
 ;   Returns #t if exit-code is 0, else returns #f
 (define (build-image args)
-  (let* ((image-type 'iso) ; todo: parse args for supported image types
+  (let* ((image-type 'iso) ; TODO: parse args for supported image types
          (image-label "nonguix-install")
-         (channel-define-name '%channels)
          (config-dir (dirname (current-filename)))
          (config-file-name "install.scm")
          (install-config (string-append config-dir
                         file-name-separator-string
                         config-file-name))
+         (name-to-search 'nonguix-channels) ; lookup in install-config
          (channels (caddr (search-for-define
                             install-config
-                            channel-define-name)))
-         (tmp-channel-file-path (make-tmp-channel (cadr channels)))
+                            name-to-search)))
+         (temp-channel-file-path (make-temp-channel (cadr channels)))
          (exit-code #f))
-    (system* "guix" "pull" (string-append "--channels=" tmp-channel-file-path))
-    (delete-file tmp-channel-file-path)
+    (system* "guix" "pull" (string-append "--channels=" temp-channel-file-path))
+    (delete-file temp-channel-file-path)
+
     (cond ((equal? image-type 'iso)
            (let ((image-link (string-append config-dir
                                file-name-separator-string
@@ -93,6 +91,8 @@
                         (string-append "--label=" image-label)
                         (string-append "--root=" image-link)
                         install-config)))))
+
     (and (member "--roll-back" args)
       (system* "guix" "pull" "--roll-back"))
+      
     (equal? exit-code 0)))
diff --git a/nongnu/system/install.scm b/nongnu/system/install.scm
index a64d190..8542c27 100644
--- a/nongnu/system/install.scm
+++ b/nongnu/system/install.scm
@@ -27,30 +27,28 @@
   #:use-module (ice-9 pretty-print)
   #:export (installation-os-nonfree))
 
-; List of guix channels for the "/etc/skel/.config/guix/channels.scm" file.
+; Guix channel for the "/etc/skel/.config/guix/channels.scm" file.
 ; %default-guix-channel is configured to pull package definitions from
 ; the Guix substitute server, to save compiling during a guix pull.
-(define %channels
- '(list (channel
-          (name 'nonguix)
-          (url "https://gitlab.com/nonguix/nonguix")
-          (introduction
-            (make-channel-introduction
-             "897c1a470da759236cc11798f4e0a5f7d4d59fbc"
-              (openpgp-fingerprint
-               "2A39 3FFF 68F4 EF7A 3D29  12AF 6F51 20A0 22FB B2D5"))))
-    (channel-with-substitutes-available
-     %default-guix-channel
-     "https://ci.guix.gnu.org")))
+(define nonguix-channels
+ '((use-modules (guix ci)) ; required for channel-with-substitutes-available
+   (list (channel
+           (name 'nonguix)
+           (url "https://gitlab.com/nonguix/nonguix")
+           (introduction
+             (make-channel-introduction
+              "897c1a470da759236cc11798f4e0a5f7d4d59fbc"
+               (openpgp-fingerprint
+                "2A39 3FFF 68F4 EF7A 3D29  12AF 6F51 20A0 22FB B2D5"))))
+     (channel-with-substitutes-available
+      %default-guix-channel
+      "https://ci.guix.gnu.org"))))
 
 ; Create the plain-file definition of "channels.scm" to add to the install.
 (define %channels-file
   (let ((port (open-output-string)))
-    (pretty-print '(use-modules
-                     (guix ci)) ; for channel-with-substitutes-availabe
-                  port)
-    (pretty-print %channels
-                  port)
+    (map (lambda (_) (pretty-print _ port))
+      nonguix-channels)
     (plain-file "channels.scm"
       (get-output-string port))))