diff --git a/pkgs/data/themes/numix/default.nix b/pkgs/data/themes/numix/default.nix
index 23f491d4a9ad..a55970d5dccf 100644
--- a/pkgs/data/themes/numix/default.nix
+++ b/pkgs/data/themes/numix/default.nix
@@ -1,19 +1,26 @@
-{ lib, stdenv, fetchFromGitHub, sass, glib, libxml2, gdk-pixbuf
+{ lib
+, stdenv
+, fetchFromGitHub
+, sassc
+, glib
+, libxml2
+, gdk-pixbuf
 , gtk-engine-murrine
+, gitUpdater
 }:
 
 stdenv.mkDerivation rec {
-  version = "2.6.7";
   pname = "numix-gtk-theme";
+  version = "unstable-2021-06-08";
 
   src = fetchFromGitHub {
     repo = "numix-gtk-theme";
     owner = "numixproject";
-    rev = version;
-    sha256 = "12mw0kr0kkvg395qlbsvkvaqccr90cmxw5rrsl236zh43kj8grb7";
+    rev = "ad4b345cb19edba96bec72d6dc97ed1b568755a8";
+    hash = "sha256-7KX5xC6Gr6azqL2qyc8rYb3q9UhcGco2uEfltsQ+mgo=";
   };
 
-  nativeBuildInputs = [ sass glib libxml2 gdk-pixbuf ];
+  nativeBuildInputs = [ sassc glib libxml2 gdk-pixbuf ];
 
   propagatedUserEnvPkgs = [ gtk-engine-murrine ];
 
@@ -22,6 +29,8 @@ stdenv.mkDerivation rec {
     patchShebangs .
   '';
 
+  passthru.updateScript = gitUpdater { };
+
   meta = {
     description = "Modern flat theme with a combination of light and dark elements (GNOME, Unity, Xfce and Openbox)";
     homepage = "https://numixproject.github.io";