diff --git a/pkgs/development/python-modules/sphinx-mdinclude/default.nix b/pkgs/development/python-modules/sphinx-mdinclude/default.nix
index ca7e574c82f..d20446e91bb 100644
--- a/pkgs/development/python-modules/sphinx-mdinclude/default.nix
+++ b/pkgs/development/python-modules/sphinx-mdinclude/default.nix
@@ -11,7 +11,7 @@
 buildPythonPackage rec {
   pname = "sphinx-mdinclude";
   version = "0.5.3";
-  format = "flit";
+  format = "pyproject";
 
   src = fetchPypi {
     pname = "sphinx_mdinclude";