diff --git a/tox.ini b/tox.ini
index 36705607c0a9f4f2688ea265a2fd01f2b4f504f2..e92d203da7b26bca7e9416b33be25266b3b2b3e6 100644
--- a/tox.ini
+++ b/tox.ini
@@ -2,7 +2,7 @@
 envlist = {py38,py39},lint,doc
 
 [testenv]
-whitelist_externals =
+allowlist_externals =
   make
 
 basepython =
@@ -14,6 +14,11 @@ basepython =
 deps =
   .[test]
 
+setenv =
+  # Force column width for functional tests since they depend on
+  # predictable output format.
+  COLUMNS=80
+
 commands =
   # Must specify cov-report explicitly, otherwise coverage starts
   # going through the tests as well.