diff --git a/tox.ini b/tox.ini
index d05a77d..6713f6e 100644
--- a/tox.ini
+++ b/tox.ini
@@ -11,7 +11,9 @@ setenv = VIRTUAL_ENV={envdir}
          LC_ALL=C
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
+whitelist_externals = find
 commands =
+  find . -type f -name "*.pyc" -delete
   python setup.py testr --testr-args='{posargs}'
 
 [testenv:flake8]