diff --git a/gnu/packages/commencement.scm b/gnu/packages/commencement.scm
index 8a0864f26a..4041d5bb89 100644
--- a/gnu/packages/commencement.scm
+++ b/gnu/packages/commencement.scm
@@ -381,7 +381,7 @@ (define mes-boot
     (inputs '())
     (propagated-inputs '())
     (native-inputs
-     `(("nyacc-source" ,(origin (inherit (package-source nyacc))
+     `(("nyacc-source" ,(origin (inherit (package-source nyacc-0.99))
                                 (snippet #f)))
        ("mes" ,%bootstrap-mes-rewired)
        ("mescc-tools" ,%bootstrap-mescc-tools)
@@ -477,7 +477,7 @@ (define tcc-boot0
     (propagated-inputs '())
     (native-inputs
      `(("mes" ,mes-boot)
-       ("nyacc-source" ,(origin (inherit (package-source nyacc))
+       ("nyacc-source" ,(origin (inherit (package-source nyacc-0.99))
                                 (snippet #f)))
        ("mescc-tools" ,%bootstrap-mescc-tools)
        ,@(%boot-gash-inputs)))
diff --git a/gnu/packages/mes.scm b/gnu/packages/mes.scm
index 9ffbe33ab7..d574071cc4 100644
--- a/gnu/packages/mes.scm
+++ b/gnu/packages/mes.scm
@@ -64,7 +64,7 @@ (define-public nyacc-0.86
     (home-page "https://savannah.nongnu.org/projects/nyacc")
     (license (list gpl3+ lgpl3+))))
 
-(define-public nyacc
+(define-public nyacc-0.99
   (package
     (inherit nyacc-0.86)
     (version "0.99.0")
@@ -95,6 +95,20 @@ (define-public nyacc
     (inputs
      `(("guile" ,guile-2.2)))))
 
+(define-public nyacc
+  (package
+    (inherit nyacc-0.99)
+    (version "1.03.0")
+    (source (origin
+              (method url-fetch)
+              (uri (string-append "mirror://savannah/nyacc/nyacc-"
+                                  version ".tar.gz"))
+              (sha256
+               (base32
+                "1vdiqpm3p0ndmpmkzcpkpjvgklfsk4wxrhkixdxbczpafdfl635p"))))
+    (inputs
+     `(("guile" ,guile-3.0)))))
+
 (define-public mes-0.19
   ;; Mes used for bootstrap.
   (package
@@ -153,7 +167,7 @@ (define-public mes
                 "0p1jsrrmcbc0zrvbvnjbb6iyxr0in71km293q8qj6gnar6bw09av"))))
     (propagated-inputs
      `(("mescc-tools" ,mescc-tools)
-       ("nyacc" ,nyacc)))
+       ("nyacc" ,nyacc-0.99)))
     (native-search-paths
      (list (search-path-specification
             (variable "C_INCLUDE_PATH")
@@ -185,7 +199,7 @@ (define-public mes-rb5
        ("make" ,gnu-make)
        ("mes" ,mes)
        ("mescc-tools" ,mescc-tools)
-       ("nyacc" ,nyacc)
+       ("nyacc" ,nyacc-0.99)
        ("sed" ,sed)
        ("tar" ,tar)))
     (supported-systems '("i686-linux"))