diff --git a/docs/contributing.md b/docs/contributing.md
index cb64e57..c173cb9 100644
--- a/docs/contributing.md
+++ b/docs/contributing.md
@@ -30,6 +30,10 @@ To see test coverage information run:
 
     bin/nosetests --with-coverage --cover-package=infi.clickhouse_orm
 
+To test with tox, ensure that the setup.py is present (otherwise run `bin/buildout buildout:develop= setup.py`) and run:
+
+    pip install tox
+    tox
 
 ---
 
diff --git a/tox.ini b/tox.ini
index e012173..81299c8 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist = py27, py35
+envlist = py27, py35, pypy
 
 [testenv]
 deps =