--- a/guix/http-client.scm
+++ b/guix/http-client.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2012, 2013, 2014 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2012, 2013, 2014, 2015 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
 ;;; Copyright © 2012, 2015 Free Software Foundation, Inc.
 ;;;
@@ -173,8 +173,8 @@ closes PORT, unless KEEP-ALIVE? is true."
  (unless (guile-version>? "2.0.9")
    ;; Guile <= 2.0.9 had a bug whereby 'response-body-port' would read more
    ;; than what 'content-length' says.  See Guile commit 802a25b.
-   (module-set! (resolve-module '(web response))
-                'make-delimited-input-port make-delimited-input-port))
+   (module-define! (resolve-module '(web response))
+                   'make-delimited-input-port make-delimited-input-port))
 
  (define (read-response-body* r)
    "Reads the response body from @var{r}, as a bytevector.  Returns