diff --git a/tox.ini b/tox.ini
index 0286b0ce8..a344bc8e8 100644
--- a/tox.ini
+++ b/tox.ini
@@ -10,10 +10,15 @@ usedevelop = True
 setenv = VIRTUAL_ENV={envdir}
 install_command = pip install -U {opts} {packages}
 deps = -r{toxinidir}/requirements.txt
-commands = python setup.py testr --slowest --testr-args='{posargs}'
+whitelist_externals = find
+commands =
+  find . -type f -name "*.pyc" -delete
+  python setup.py testr --slowest --testr-args='{posargs}'
 
 [testenv:venv]
 commands = {posargs}
 
 [testenv:docs]
-commands = python setup.py build_sphinx
+commands =
+  find . -type f -name "*.pyc" -delete
+  python setup.py build_sphinx