diff --git a/setup.cfg b/setup.cfg
index 228fb3b47..64ade7efb 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -12,9 +12,7 @@ multi_line_output=4
 skip=migrations,project_template
 add_imports=from __future__ import absolute_import,from __future__ import unicode_literals
 known_first_party=wagtail
-
-# These dependencies are frequently installed in "develop" mode which may cause isort to detect them as first party
-known_third_party=willow,modelcluster,taggit,django
+known_third_party=willow,modelcluster,taggit,django,unidecode,bs4,pytz,PIL
 
 [pytest]
 django_find_project = false