diff --git a/tox.ini b/tox.ini
index 01c0ed772d..d2128cb9dc 100644
--- a/tox.ini
+++ b/tox.ini
@@ -40,6 +40,8 @@ extras =
 	docs
 	testing
 changedir = docs
+deps =
+	importlib_resources < 6  # twisted/towncrier#528 (waiting for release)
 commands =
 	python -m sphinx -W --keep-going . {toxinidir}/build/html
 	python -m sphinxlint
@@ -50,6 +52,7 @@ deps =
 	towncrier
 	bump2version
 	jaraco.develop >= 7.23
+	importlib_resources < 6  # twisted/towncrier#528 (waiting for release)
 passenv = *
 commands =
 	python tools/finalize.py