diff --git a/requirements-test.txt b/requirements-test.txt
index ed935ea9..d5f8088c 100644
--- a/requirements-test.txt
+++ b/requirements-test.txt
@@ -1,4 +1,5 @@
 -r requirements.txt
 
+flake8
 nose
 ordereddict # Python 2.6
diff --git a/tox.ini b/tox.ini
index 96f9c3b4..fe6358ae 100644
--- a/tox.ini
+++ b/tox.ini
@@ -4,6 +4,7 @@ envlist = py26,py27,py32,py33
 [testenv]
 deps =
   -r{toxinidir}/requirements-optional-cpython.txt
+  flake8
   nose
 commands =
   {envbindir}/nosetests -q
@@ -14,6 +15,7 @@ commands =
 # (it's slower than the pure-python version)
 deps =
   charade
+  flake8
   Genshi
   nose
   six
@@ -22,4 +24,5 @@ deps =
 basepython = python2.6
 deps =
   -r{toxinidir}/requirements-optional-2.6.txt
+  flake8
   nose