diff --git a/pkgs/development/python-modules/whisper/default.nix b/pkgs/development/python-modules/whisper/default.nix
index 1fb9dd6da16..d78d39d9d7a 100644
--- a/pkgs/development/python-modules/whisper/default.nix
+++ b/pkgs/development/python-modules/whisper/default.nix
@@ -1,4 +1,4 @@
-{ stdenv, buildPythonPackage, fetchPypi, six }:
+{ stdenv, buildPythonPackage, fetchPypi, six, mock }:
 
 buildPythonPackage rec {
   pname = "whisper";
@@ -11,6 +11,8 @@ buildPythonPackage rec {
 
   propagatedBuildInputs = [ six ];
 
+  checkInputs = [ mock ];
+
   meta = with stdenv.lib; {
     homepage = http://graphite.wikidot.com/;
     description = "Fixed size round-robin style database";