diff --git a/pkgs/development/tools/parsing/byacc/default.nix b/pkgs/development/tools/parsing/byacc/default.nix
index ce8f7de1bbb..612196cba77 100644
--- a/pkgs/development/tools/parsing/byacc/default.nix
+++ b/pkgs/development/tools/parsing/byacc/default.nix
@@ -2,14 +2,14 @@
 
 stdenv.mkDerivation rec {
   name = "byacc-${version}";
-  version = "20170201";
+  version = "20170709";
 
   src = fetchurl {
     urls = [
       "ftp://ftp.invisible-island.net/byacc/${name}.tgz"
       "https://invisible-mirror.net/archives/byacc/${name}.tgz"
     ];
-    sha256 = "90b768d177f91204e6e7cef226ae1dc7cac831b625774cebd3e233a917754f91";
+    sha256 = "1syrg1nwh2qmlr5mh7c4vz9psdv4gf55h8i5ffw84q6whlcq1kr7";
   };
 
   doCheck = true;