diff --git a/pkgs/development/python-modules/cytoolz/default.nix b/pkgs/development/python-modules/cytoolz/default.nix
index 156cd0f5a4c..0e72ecaa825 100644
--- a/pkgs/development/python-modules/cytoolz/default.nix
+++ b/pkgs/development/python-modules/cytoolz/default.nix
@@ -6,20 +6,19 @@
 , toolz
 , python
 , fetchpatch
+, isPy27
 }:
 
 buildPythonPackage rec {
   pname = "cytoolz";
   version = "0.11.0";
+  disabled = isPy27 || isPyPy;
 
   src = fetchPypi {
     inherit pname version;
     sha256 = "c64f3590c3eb40e1548f0d3c6b2ccde70493d0b8dc6cc7f9f3fec0bb3dcd4222";
   };
 
-  # Extension types
-  disabled = isPyPy;
-
   checkInputs = [ nose ];
   propagatedBuildInputs = [ toolz ];