diff --git a/requirements/constraints.txt b/requirements/constraints.txt
index 3bd16e635..87a5e5582 100644
--- a/requirements/constraints.txt
+++ b/requirements/constraints.txt
@@ -18,3 +18,7 @@ django<4.3
 
 # urllib3 > 2.0.2 introduces an error
 urllib3>=1.26.15, <2
+
+# tox>4.0.0 isn't yet compatible with many tox plugins, causing CI failures in almost all repos.
+# Details can be found in this discussion: https://github.com/tox-dev/tox/discussions/1810
+tox<4.0.0