diff --git a/pkgs/development/python-modules/werkzeug/default.nix b/pkgs/development/python-modules/werkzeug/default.nix
index 5979d895a74..254897be78b 100644
--- a/pkgs/development/python-modules/werkzeug/default.nix
+++ b/pkgs/development/python-modules/werkzeug/default.nix
@@ -1,21 +1,23 @@
 { stdenv, buildPythonPackage, fetchPypi
-, itsdangerous
+, itsdangerous, hypothesis
 , pytest, requests, glibcLocales }:
 
 buildPythonPackage rec {
   name = "${pname}-${version}";
   pname = "Werkzeug";
-  version = "0.12.2";
+  version = "0.13";
 
   src = fetchPypi {
     inherit pname version;
-    sha256 = "09mv4cya3lywkn4mi3qrqmjgwiw99kdk03dk912j8da6ny3pnflh";
+    sha256 = "6246e5fc98a505824113fb6aca993d45ea284a2bcffdc2c65d0c538e53e4abd3";
   };
 
-  LC_ALL = "en_US.UTF-8";
-
   propagatedBuildInputs = [ itsdangerous ];
-  buildInputs = [ pytest requests glibcLocales ];
+  checkInputs = [ pytest requests glibcLocales hypothesis ];
+
+  checkPhase = ''
+    LC_ALL="en_US.UTF-8" py.test
+  '';
 
   meta = with stdenv.lib; {
     homepage = http://werkzeug.pocoo.org/;