diff --git a/tox.ini b/tox.ini
index dd43622..782460d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -11,6 +11,7 @@ deps =
     brunns-builder>=0.5
     lovely-pytest-docker>=0.3.1
     docker-compose>=1.29
+    Cython<3.0
 commands =
     {posargs:py.test}
 extras = optional