diff --git a/tox.ini b/tox.ini
index 6205cc5..efdb45e 100644
--- a/tox.ini
+++ b/tox.ini
@@ -25,7 +25,10 @@ commands = flake8 {posargs}
 commands = {posargs}
 
 [testenv:cover]
-commands = python setup.py test --coverage --testr-args='{posargs}'
+commands =
+  coverage erase
+  find . -type f -name "*.pyc" -delete
+  python setup.py testr --coverage --testr-args='{posargs}'
 
 [testenv:docs]
 commands = python setup.py build_sphinx