diff --git a/gnu/packages/guile.scm b/gnu/packages/guile.scm
index 16e96848d60c0c0749a32485c05c1205232846b0..0b1cc34335bb2a689eb8792a232e1196a88198cd 100644
--- a/gnu/packages/guile.scm
+++ b/gnu/packages/guile.scm
@@ -331,14 +331,14 @@ (define-public guile-lib
 (define-public guile-json
   (package
     (name "guile-json")
-    (version "0.3.1")
+    (version "0.4.0")
     (source (origin
              (method url-fetch)
              (uri (string-append "mirror://savannah/guile-json/guile-json-"
                                  version ".tar.gz"))
              (sha256
               (base32
-               "0nz2sx61kd6cfflwzxxq0cb9dz0asb81abbhfawv4p9ghciqdr3g"))
+               "0v06272rw4ycwzssjf3fzpk2vhpslvl55hz94q80vc6f74j0d5h6"))
              (modules '((guix build utils)))
              (snippet
               ;; Make sure everything goes under .../site/2.0, like Guile's