diff --git a/pkgs/development/python-modules/flask/default.nix b/pkgs/development/python-modules/flask/default.nix
index b16dc08a5e1..5e77de84fed 100644
--- a/pkgs/development/python-modules/flask/default.nix
+++ b/pkgs/development/python-modules/flask/default.nix
@@ -1,5 +1,5 @@
 { stdenv, buildPythonPackage, fetchPypi
-, itsdangerous, click, werkzeug, jinja2 }:
+, itsdangerous, click, werkzeug, jinja2, pytest }:
 
 buildPythonPackage rec {
   name = "${pname}-${version}";
@@ -11,8 +11,16 @@ buildPythonPackage rec {
     sha256 = "1hfs2jr2m5lr51xd4gblb28rncd0xrpycz6c07cyqsbv4dhl9x29";
   };
 
+  checkInputs = [ pytest ];
   propagatedBuildInputs = [ itsdangerous click werkzeug jinja2 ];
 
+  checkPhase = ''
+    py.test
+  '';
+
+  # Tests require extra dependencies
+  doCheck = false;
+
   meta = with stdenv.lib; {
     homepage = http://flask.pocoo.org/;
     description = "A microframework based on Werkzeug, Jinja 2, and good intentions";