diff --git a/tox.ini b/tox.ini
index d7a14ff4..43826a2e 100644
--- a/tox.ini
+++ b/tox.ini
@@ -13,8 +13,9 @@ install_command = {toxinidir}/tools/tox_install.sh {opts} {packages}
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 whitelist_externals = sh
-commands =
-  sh tools/pretty_tox.sh '{posargs}'
+                      find
+commands = find . -type f -name "*.py[c|o]" -delete
+           sh tools/pretty_tox.sh '{posargs}'
 
 [testenv:pep8]
 commands = flake8