diff --git a/tests/README.markdown b/tests/README.markdown
index 320b5b3..793ae68 100644
--- a/tests/README.markdown
+++ b/tests/README.markdown
@@ -12,11 +12,16 @@ They run very quickly and don't require any external test hosts.
 #### Requirements
  * mock >= 1.0.0
  * httpretty >= 0.6.1
+ * tox (optional)
 
 #### Running the Unit Tests
 
     python -m unittest discover tests/unit
 
+To run the unit tests against all supported Python versions, use ```tox```:
+    
+    tox
+
 ----------------------------------------
 
 ###Functional Tests