diff --git a/pkgs/by-name/un/unordered_dense/package.nix b/pkgs/by-name/un/unordered_dense/package.nix
index 7f541678efa6..48ed5057d4e6 100644
--- a/pkgs/by-name/un/unordered_dense/package.nix
+++ b/pkgs/by-name/un/unordered_dense/package.nix
@@ -6,13 +6,13 @@
 }:
 stdenv.mkDerivation (finalAttrs: {
   pname = "unordered_dense";
-  version = "4.8.1";
+  version = "4.9.0";
 
   src = fetchFromGitHub {
     owner = "martinus";
     repo = "unordered_dense";
     tag = "v${finalAttrs.version}";
-    hash = "sha256-JdPlyShWnAcdgixDHRaroFg7YWdPtD4Nl1PmpcQ1SAk=";
+    hash = "sha256-M8eBkoTVnZ1sjvLIQ3aObaxZyephXcvmpIh1bc6T5Ik=";
   };
 
   nativeBuildInputs = [ cmake ];