diff --git a/tox.ini b/tox.ini
index ae061c3..0e61a56 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-minversion = 3.1.1
+minversion = 3.18.0
 envlist = py3,pep8
 ignore_basepython_conflict = True
 
@@ -34,14 +34,14 @@ commands =
 
 [testenv:docs]
 deps = -r{toxinidir}/doc/requirements.txt
-Allowlist_externals =
+allowlist_externals =
   rm
 commands =
   rm -fr doc/build
   sphinx-build -E -W --keep-going -b html doc/source doc/build/html
 
 [testenv:releasenotes]
-Allowlist_externals =
+allowlist_externals =
   rm
 commands =
   rm -rf releasenotes/build