diff --git a/pkgs/development/python-modules/cynthion/default.nix b/pkgs/development/python-modules/cynthion/default.nix
index 0ed5832bef9c..b61edaeda1db 100644
--- a/pkgs/development/python-modules/cynthion/default.nix
+++ b/pkgs/development/python-modules/cynthion/default.nix
@@ -51,6 +51,8 @@ buildPythonPackage rec {
     setuptools
   ];
 
+  pythonRelaxDeps = [ "pygreat" ];
+
   pythonRemoveDeps = [ "future" ];
 
   dependencies = [
diff --git a/pkgs/development/python-modules/pygreat/default.nix b/pkgs/development/python-modules/pygreat/default.nix
index bb3bd2ee8f10..bee64dd72b55 100644
--- a/pkgs/development/python-modules/pygreat/default.nix
+++ b/pkgs/development/python-modules/pygreat/default.nix
@@ -8,14 +8,14 @@
 
 buildPythonPackage rec {
   pname = "pygreat";
-  version = "2024.0.5";
+  version = "2026.0.0";
   pyproject = true;
 
   src = fetchFromGitHub {
     owner = "greatscottgadgets";
     repo = "libgreat";
     tag = "v${version}";
-    hash = "sha256-2PFeCG7m8qiK3eBX2838P6ZsLoQxcJBG+/TppUMT6dE=";
+    hash = "sha256-m+s2TAJK7UhKWbuSd5ec1O40WeMXxJyTD9yqPOr0LEM=";
   };
 
   sourceRoot = "${src.name}/host";
@@ -26,8 +26,6 @@ buildPythonPackage rec {
       --replace-fail 'dynamic = ["version"]' 'version = "${version}"'
   '';
 
-  pythonRemoveDeps = [ "backports.functools_lru_cache" ];
-
   build-system = [ setuptools ];
 
   dependencies = [ pyusb ];