diff --git a/tox.ini b/tox.ini
index 19f4276..ec4d6ce 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,31 +1,32 @@
 [tox]
 envlist=flake8,mypy,py3
 
 [testenv]
 passenv=SWH_KAFKA_ROOT
 extras =
   testing
 deps =
   pytest-cov
+  dev: pdbpp
 setenv =
   SWH_KAFKA_ROOT = {env:SWH_KAFKA_ROOT:swh/journal/tests/kafka}
 commands =
   pytest --cov={envsitepackagesdir}/swh/journal \
          {envsitepackagesdir}/swh/journal \
          --cov-branch \
          --doctest-modules {posargs}
 
 [testenv:flake8]
 skip_install = true
 deps =
   flake8
 commands =
   {envpython} -m flake8
 
 [testenv:mypy]
 extras =
   testing
 deps =
   mypy
 commands =
   mypy swh