diff --git a/tox.ini b/tox.ini
index 68d2e6a61..79603cda9 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,11 +1,27 @@
+# tox configuration - if you change anything here, run this to verify:
+# fakeroot -u tox --recreate
+#
+# Invokation examples:
+# fakeroot -u tox  # run all tests
+# fakeroot -u tox -e py32  # run all tests, but only on python 3.2
+# fakeroot -u tox borg.testsuite.locking  # only run 1 test module
+# fakeroot -u tox borg.testsuite.locking -- -k '"not Timer"'  # exclude some tests
+# fakeroot -u tox borg.testsuite -- -v  # verbose py.test
+#
+# Important notes:
+# Without fakeroot -u some tests will fail.
+# When using -- to give options to py.test, you MUST also give borg.testsuite[.module].
+
 [tox]
 envlist = py32, py33, py34
 
 [testenv]
-# Change dir to avoid import problem
-changedir = {envdir}
+# Change dir to avoid import problem for cython code. The directory does
+# not really matter, should be just different from the toplevel dir.
+changedir = {toxworkdir}
 deps =
     pytest
     mock
-commands = py.test
-passenv = *  # fakeroot -u needs some env vars
+commands = py.test --pyargs {posargs:borg.testsuite}
+# fakeroot -u needs some env vars:
+passenv = *