diff --git a/pkgs/development/python-modules/warlock/default.nix b/pkgs/development/python-modules/warlock/default.nix
index b0352114cf66..6ad45ae49fa7 100644
--- a/pkgs/development/python-modules/warlock/default.nix
+++ b/pkgs/development/python-modules/warlock/default.nix
@@ -7,6 +7,7 @@
   jsonpatch,
   jsonschema,
   pytestCheckHook,
+  pytest-cov-stub,
 }:
 
 buildPythonPackage rec {
@@ -23,10 +24,6 @@ buildPythonPackage rec {
     hash = "sha256-HOCLzFYmOL/tCXT+NO/tCZuVXVowNEPP3g33ZYg4+6Q=";
   };
 
-  postPatch = ''
-    sed -i '/--cov/d' pytest.ini
-  '';
-
   nativeBuildInputs = [ poetry-core ];
 
   propagatedBuildInputs = [
@@ -34,7 +31,10 @@ buildPythonPackage rec {
     jsonschema
   ];
 
-  nativeCheckInputs = [ pytestCheckHook ];
+  nativeCheckInputs = [
+    pytestCheckHook
+    pytest-cov-stub
+  ];
 
   disabledTests = [
     # https://github.com/bcwaldon/warlock/issues/64