diff --git a/flake.nix b/flake.nix
index b9c86e9..10a2150 100644
--- a/flake.nix
+++ b/flake.nix
@@ -16,6 +16,22 @@
       py = pkgs.python3.override {
         packageOverrides = final: prev: {
           django = prev.django_4;
+          cronsim =
+            let
+              version = "2.5";
+              pname = "cronsim";
+              src = pkgs.fetchPypi {
+                inherit pname version;
+                hash = "sha256-FTzwIZ3MGgyp5xqDav22B5ZTfYxSHGhsenMTSDdXM78=";
+              };
+            in
+            prev.buildPythonPackage {
+              inherit pname version src;
+              # nativeCheckInputs = [ prev.pytestCheckHook ];
+              pythonImportsCheck = [
+                "cronsim"
+              ];
+            };
         };
       };
       baseImage = {