diff --git a/lib/.keep b/lib/.keep
new file mode 100644
index 0000000..f49b91a
--- /dev/null
+++ b/lib/.keep
@@ -0,0 +1,3 @@
+  This file was created by release-tools to ensure that this empty
+  directory is preserved in vcs re: lint check definitions in global
+  tox.ini files. This file can be removed if/when this dir is actually in use.
diff --git a/tox.ini b/tox.ini
index 491ccf1..d8d8d03 100644
--- a/tox.ini
+++ b/tox.ini
@@ -8,6 +8,7 @@ skipsdist = True
 [testenv]
 setenv = VIRTUAL_ENV={envdir}
          PYTHONHASHSEED=0
+         CHARM_DIR={envdir}
          AMULET_SETUP_TIMEOUT=2700
 install_command =
   pip install --allow-unverified python-apt {opts} {packages}
@@ -24,7 +25,7 @@ deps = -r{toxinidir}/requirements.txt
 basepython = python2.7
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
-commands = flake8 {posargs} hooks unit_tests tests actions
+commands = flake8 {posargs} hooks unit_tests tests actions lib
            charm-proof
 
 [testenv:venv]