diff --git a/pkgs/development/python-modules/envs/default.nix b/pkgs/development/python-modules/envs/default.nix
index e39292049da08..600cb3b0320ef 100644
--- a/pkgs/development/python-modules/envs/default.nix
+++ b/pkgs/development/python-modules/envs/default.nix
@@ -1,5 +1,6 @@
 { lib, buildPythonPackage, fetchPypi
-, click, jinja2, terminaltables }:
+, mock, jinja2, click, terminaltables
+}:
 
 buildPythonPackage rec {
   pname = "envs";
@@ -10,7 +11,7 @@ buildPythonPackage rec {
     sha256 = "ccf5cd85ddb8ed335e39ed8a22e0d23658f5a6d7da430f225e6f750c6f50ae42";
   };
 
-  checkInputs = [ click jinja2 terminaltables ];
+  checkInputs = [ mock jinja2 click terminaltables ];
 
   meta = with lib; {
     description = "Easy access to environment variables from Python";