diff --git a/pkgs/development/tools/language-servers/ruff-lsp/default.nix b/pkgs/development/tools/language-servers/ruff-lsp/default.nix
index 4f4304017c4a..abd9bbb52c97 100644
--- a/pkgs/development/tools/language-servers/ruff-lsp/default.nix
+++ b/pkgs/development/tools/language-servers/ruff-lsp/default.nix
@@ -16,7 +16,7 @@
 buildPythonPackage rec {
   pname = "ruff-lsp";
   version = "0.0.39";
-  format = "pyproject";
+  pyproject = true;
   disabled = pythonOlder "3.7";
 
   src = fetchFromGitHub {