diff --git a/pkgs/development/python-modules/rubymarshal/default.nix b/pkgs/development/python-modules/rubymarshal/default.nix
index 0e2ada2d063c..11b1ec990727 100644
--- a/pkgs/development/python-modules/rubymarshal/default.nix
+++ b/pkgs/development/python-modules/rubymarshal/default.nix
@@ -2,14 +2,14 @@
   lib,
   buildPythonPackage,
   fetchPypi,
-  hypothesis,
+  poetry-core,
   isPy3k,
 }:
 
 buildPythonPackage rec {
   pname = "rubymarshal";
   version = "1.2.8";
-  format = "setuptools";
+  pyproject = true;
   disabled = !isPy3k;
 
   src = fetchPypi {
@@ -17,7 +17,7 @@ buildPythonPackage rec {
     sha256 = "sha256-8+8KxCjsawlFXd1Bgq/8jY0TSB9l8UHaNMkcqfoz7hs=";
   };
 
-  propagatedBuildInputs = [ hypothesis ];
+  build-system = [ poetry-core ];
 
   # pypi doesn't distribute tests
   doCheck = false;