diff --git a/pkgs/development/python-modules/udatetime/default.nix b/pkgs/development/python-modules/udatetime/default.nix
index e161e0f00ff6..fb4388ac9302 100644
--- a/pkgs/development/python-modules/udatetime/default.nix
+++ b/pkgs/development/python-modules/udatetime/default.nix
@@ -2,18 +2,21 @@
   lib,
   buildPythonPackage,
   fetchPypi,
+  setuptools,
 }:
 
 buildPythonPackage rec {
   pname = "udatetime";
   version = "0.0.17";
-  format = "setuptools";
+  pyproject = true;
 
   src = fetchPypi {
     inherit pname version;
     hash = "sha256-sQvFVwaZpDinLitaZOdr2MKO4779FvIJOHpVB/oLgwE=";
   };
 
+  build-system = [ setuptools ];
+
   # tests not included on pypi
   doCheck = false;