diff --git a/tox.ini b/tox.ini
index cc68d315..eff0e9f9 100644
--- a/tox.ini
+++ b/tox.ini
@@ -12,9 +12,9 @@ setenv =
 
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
-commands = sh -c 'find . -not \( -type d -name .?\* -prune \) \
+commands = sh -c '(find . -not \( -type d -name .?\* -prune \) \
            \( -type d -name "__pycache__" -or -type f -name "*.py[co]" \) \
-           -print0 | xargs -0 rm -rf'
+           -print0; find . -name "*.dbm*" -print0) | xargs -0 rm -rf'
            python setup.py testr --testr-args="{posargs}"
 whitelist_externals = sh
 passenv = SWIFT_* *_proxy