diff --git a/qutebrowser/misc/crashsignal.py b/qutebrowser/misc/crashsignal.py
index 22ed92dea..47e70d808 100644
--- a/qutebrowser/misc/crashsignal.py
+++ b/qutebrowser/misc/crashsignal.py
@@ -22,7 +22,7 @@
 import os
 import sys
 import bdb
-import pdb
+import pdb  # noqa
 import signal
 import functools
 import faulthandler
diff --git a/tox.ini b/tox.ini
index 12ee382b4..d20f3ceda 100644
--- a/tox.ini
+++ b/tox.ini
@@ -153,6 +153,7 @@ passenv =
 deps =
     -r{toxinidir}/requirements.txt
     flake8==2.5.1
+    flake8-debugger==1.4.0
     mccabe==0.3.1
     pep8==1.7.0
     pyflakes==1.0.0