diff --git a/gnu/packages/mes.scm b/gnu/packages/mes.scm
index f14d58d5a..84d6f8ff7 100644
--- a/gnu/packages/mes.scm
+++ b/gnu/packages/mes.scm
@@ -37,18 +37,19 @@
     (version "0.78.3")
     (source (origin
               (method url-fetch)
-              (uri (string-append
-                    "https://download.savannah.gnu.org/releases/nyacc/"
+              (uri (string-append "mirror://savannah/nyacc/"
                                   name "-" version ".tar.gz"))
               (sha256
-               (base32 "0xrnl2hl9rpl50n8cihvclcd951zj640fj5kpi3d6ihwcqjcdi0a"))))
+               (base32
+                "0xrnl2hl9rpl50n8cihvclcd951zj640fj5kpi3d6ihwcqjcdi0a"))))
     (build-system gnu-build-system)
     (native-inputs
      `(("guile" ,guile-2.2)))
     (synopsis "LALR(1) Parser Generator in Guile")
     (description
-     "NYACC is a LALR(1) Parser Generator Implemented in Guile.
-The syntax and nomenclature should be considered not stable.")
+     "NYACC is an LALR(1) parser generator implemented in Guile.
+The syntax and nomenclature should be considered not stable.  It comes with
+extensive examples, including parsers for the Javascript and C99 languages.")
     (home-page "https://savannah.nongnu.org/projects/nyacc")
     (license (list gpl3+ lgpl3+))))