diff --git a/guix/scripts/challenge.scm b/guix/scripts/challenge.scm
index ebeebd5cbe2cb07ba3db7db78732ee8ae1f363be..65e2427033b9267e4458bcd1dafd002150d7ad08 100644
--- a/guix/scripts/challenge.scm
+++ b/guix/scripts/challenge.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2015, 2016, 2017, 2019 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2015, 2016, 2017, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -25,7 +25,7 @@ (define-module (guix scripts challenge)
   #:use-module (guix monads)
   #:use-module (guix base32)
   #:use-module (guix packages)
-  #:use-module (guix progress)
+  #:use-module ((guix progress) #:hide (dump-port*))
   #:use-module (guix serialization)
   #:use-module (guix scripts substitute)
   #:use-module (rnrs bytevectors)
@@ -193,9 +193,6 @@ (define (select-reference item narinfos urls)
 ;;; Reporting.
 ;;;
 
-(define dump-port*                                ;FIXME: deduplicate
-  (@@ (guix serialization) dump))
-
 (define (port-sha256* port size)
   ;; Like 'port-sha256', but limited to SIZE bytes.
   (let-values (((out get) (open-sha256-port)))
diff --git a/guix/serialization.scm b/guix/serialization.scm
index f793feb53dcc899fac98abf5ebbb48034cd387d0..9452303730b3292ba62e49c5ab5028e1d0700e8c 100644
--- a/guix/serialization.scm
+++ b/guix/serialization.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -36,6 +36,7 @@ (define-module (guix serialization)
             write-string-pairs
             write-store-path read-store-path
             write-store-path-list read-store-path-list
+            (dump . dump-port*)
 
             &nar-error
             nar-error?