diff --git a/tox.ini b/tox.ini
index 40978d654..53fa8719f 100644
--- a/tox.ini
+++ b/tox.ini
@@ -11,7 +11,9 @@ setenv = VIRTUAL_ENV={envdir}
 
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
-commands = python setup.py testr --testr-args='{posargs}'
+commands =
+  find . -type f -name "*.pyc" -delete
+  python setup.py testr --testr-args='{posargs}'
 
 [testenv:pep8]
 commands = flake8 {posargs}