diff --git a/pkgs/development/python-modules/sphinx-multitoc-numbering/default.nix b/pkgs/development/python-modules/sphinx-multitoc-numbering/default.nix
index 612717120f83..33e346638e9c 100644
--- a/pkgs/development/python-modules/sphinx-multitoc-numbering/default.nix
+++ b/pkgs/development/python-modules/sphinx-multitoc-numbering/default.nix
@@ -7,6 +7,7 @@
 buildPythonPackage rec {
   pname = "sphinx-multitoc-numbering";
   version = "0.1.3";
+  format = "pyproject";
 
   src = fetchPypi {
     inherit pname version;