diff --git a/pkgs/development/libraries/ace/default.nix b/pkgs/development/libraries/ace/default.nix
index e0c46acb6303..75c942d4d487 100644
--- a/pkgs/development/libraries/ace/default.nix
+++ b/pkgs/development/libraries/ace/default.nix
@@ -2,11 +2,11 @@
 
 stdenv.mkDerivation rec {
   name = "ace-${version}";
-  version = "6.5.5";
+  version = "6.5.6";
 
   src = fetchurl {
     url = "http://download.dre.vanderbilt.edu/previous_versions/ACE-${version}.tar.bz2";
-    sha256 = "1r1bvy65n50l6lbxm1k1bscqcv29mpkgp0pgr5cvvv7ldisrjl39";
+    sha256 = "15lfjc8r854hvjfvimhnqc3987b3cdngilhkii9rwpzginbyipi4";
   };
 
   enableParallelBuilding = true;