diff --git a/pkgs/development/python-modules/cons/default.nix b/pkgs/development/python-modules/cons/default.nix
index 2977051d87b..03017a53615 100644
--- a/pkgs/development/python-modules/cons/default.nix
+++ b/pkgs/development/python-modules/cons/default.nix
@@ -2,6 +2,7 @@
 , buildPythonPackage
 , fetchFromGitHub
 , logical-unification
+, py
 , pytestCheckHook
 , pytest-html
 }:
@@ -22,6 +23,7 @@ buildPythonPackage rec {
   ];
 
   checkInputs = [
+    py
     pytestCheckHook
     pytest-html
   ];