--- a/tox.ini	Tue Oct 24 09:50:29 2017 +0200
+++ b/tox.ini	Mon Oct 30 09:04:34 2017 +0100
@@ -20,7 +20,7 @@
 [testenv:flake8]
 skip_install = true
 deps =
-  flake8 >= 3
+  flake8 >= 3.4, < 3.5
 whitelist_externals =
   /bin/sh
 commands = /bin/sh -c "flake8 `xargs -a {toxinidir}/flake8-ok-files.txt`"