diff --git a/tox.ini b/tox.ini
index efcd0c5..6774c89 100644
--- a/tox.ini
+++ b/tox.ini
@@ -25,6 +25,7 @@ deps =
     pytest73: pytest==7.3.*
     pytest74: pytest==7.4.*
     pytestdev: git+https://github.com/pytest-dev/pytest#egg=pytest
+    pytestdev: git+https://github.com/scientific-python/pytest-doctestplus
 
 extras =
     test