diff --git a/tox.ini b/tox.ini
index a22db72..2ca724a 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,26 +1,27 @@
 [tox]
 envlist=flake8,py3
 
 [testenv:py3]
 deps =
   swh.core[http] >= 0.0.61
   .[testing]
   pytest-cov
 commands =
   pytest --cov={envsitepackagesdir}/swh/lister/ --cov-branch \
          {envsitepackagesdir}/swh/lister/ {posargs}
 
 [testenv:py3-dev]
 deps =
   swh.core[http] >= 0.0.61
   .[testing]
   pytest-cov
+  ipdb
 commands =
   pytest {envsitepackagesdir}/swh/lister/ {posargs}
 
 [testenv:flake8]
 skip_install = true
 deps =
   flake8
 commands =
   {envpython} -m flake8