diff --git a/tox.ini b/tox.ini
index 79ea939..6dc83f7 100644
--- a/tox.ini
+++ b/tox.ini
@@ -17,6 +17,14 @@
 commands =
   python setup.py testr --slowest --testr-args='{posargs}'
 
+[testenv:bindep]
+# Do not install any requirements. We want this to be fast and work even if
+# system dependencies are missing, since it's used to tell you what system
+# dependencies are missing! This also means that bindep must be installed
+# separately, outside of the requirements files.
+deps = bindep
+commands = bindep test
+
 [testenv:pep8]
 commands = flake8 {posargs}