diff --git a/pkgs/development/python-modules/python-datemath/default.nix b/pkgs/development/python-modules/python-datemath/default.nix
index dbe968a8f01f..44b05d8fa72d 100644
--- a/pkgs/development/python-modules/python-datemath/default.nix
+++ b/pkgs/development/python-modules/python-datemath/default.nix
@@ -4,32 +4,34 @@
   buildPythonPackage,
   fetchFromGitHub,
   fetchpatch,
-  pythonOlder,
-  pytestCheckHook,
   freezegun,
+  pytestCheckHook,
+  pythonOlder,
   pytz,
+  setuptools,
 }:
 
 buildPythonPackage rec {
   pname = "python-datemath";
   version = "3.0.1";
-  format = "setuptools";
+  pyproject = true;
 
   disabled = pythonOlder "3.8";
 
   src = fetchFromGitHub {
     owner = "nickmaccarthy";
-    repo = pname;
+    repo = "python-datemath";
     rev = "refs/tags/v${version}";
     hash = "sha256-BL+F2oHM49QiwV1/rjXz3wLp+EaTfmc5tAdlsGKq8ag=";
   };
 
+  build-system = [ setuptools ];
+
   dependencies = [ arrow ];
 
-  nativeCheckInputs = [ pytestCheckHook ];
-
-  checkInputs = [
+  nativeCheckInputs = [
     freezegun
+    pytestCheckHook
     pytz
   ];
 
@@ -40,7 +42,7 @@ buildPythonPackage rec {
   meta = {
     description = "Python module to emulate the date math used in SOLR and Elasticsearch";
     homepage = "https://github.com/nickmaccarthy/python-datemath";
-     changelog = "https://github.com/nickmaccarthy/python-datemath/blob/v${version}/CHANGELOG.md";
+    changelog = "https://github.com/nickmaccarthy/python-datemath/blob/v${version}/CHANGELOG.md";
     license = with lib.licenses; [ asl20 ];
     maintainers = with lib.maintainers; [ fab ];
   };