diff --git a/tox.ini b/tox.ini
index d553d24..e2876ad 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-minversion = 3.9.0
+minversion = 3.18.0
 envlist = pep8
 skipsdist = True
 ignore_basepython_conflict = true
@@ -33,7 +33,7 @@ commands = sphinx-build -W -b html doc/source doc/build/html
 
 [testenv:pdf-docs]
 usedevelop = False
-whitelist_externals = make
+allowlist_externals = make
 commands = sphinx-build -b latex doc/source doc/build/pdf
            make -C doc/build/pdf