diff --git a/src/jupyter_contrib_nbextensions/nbconvert_support/collapsible_headings.py b/src/jupyter_contrib_nbextensions/nbconvert_support/collapsible_headings.py
index 9fc0c71..a6b6526 100644
--- a/src/jupyter_contrib_nbextensions/nbconvert_support/collapsible_headings.py
+++ b/src/jupyter_contrib_nbextensions/nbconvert_support/collapsible_headings.py
@@ -6,6 +6,7 @@ import os
 from notebook.services.config import ConfigManager
 
 from jupyter_contrib_nbextensions import __file__ as contrib_init
+
 from .exporter_inliner import ExporterInliner
 
 
diff --git a/src/jupyter_contrib_nbextensions/nbconvert_support/embedhtml.py b/src/jupyter_contrib_nbextensions/nbconvert_support/embedhtml.py
index 4e16255..426093c 100644
--- a/src/jupyter_contrib_nbextensions/nbconvert_support/embedhtml.py
+++ b/src/jupyter_contrib_nbextensions/nbconvert_support/embedhtml.py
@@ -1,10 +1,11 @@
 """Embed graphics into HTML Exporter class"""
 
 import base64
-import re
-from nbconvert.exporters.html import HTMLExporter
-from ipython_genutils.ipstruct import Struct
 import os
+import re
+
+from ipython_genutils.ipstruct import Struct
+from nbconvert.exporters.html import HTMLExporter
 
 try:
     from urllib.request import urlopen  # py3
diff --git a/src/jupyter_contrib_nbextensions/nbconvert_support/toc2.py b/src/jupyter_contrib_nbextensions/nbconvert_support/toc2.py
index 62022e3..c6ed92e 100644
--- a/src/jupyter_contrib_nbextensions/nbconvert_support/toc2.py
+++ b/src/jupyter_contrib_nbextensions/nbconvert_support/toc2.py
@@ -14,6 +14,7 @@
 from nbconvert.exporters.html import HTMLExporter
 from traitlets.config import Config
 
+
 # -----------------------------------------------------------------------------
 # Classes
 # -----------------------------------------------------------------------------
diff --git a/tests/test_exporters.py b/tests/test_exporters.py
index 834db9f..8c3816a 100644
--- a/tests/test_exporters.py
+++ b/tests/test_exporters.py
@@ -3,8 +3,8 @@
 
 import io
 import os
-
 from functools import wraps
+
 from nbconvert.tests.base import TestsBase
 from nbformat import v4, write
 
diff --git a/tox.ini b/tox.ini
index 79ce2cd..00a1517 100644
--- a/tox.ini
+++ b/tox.ini
@@ -63,7 +63,7 @@ deps =
     flake8
     isort
 commands =
-    flake8 src tests setup.py
+    flake8 --max-line-length=120 src tests setup.py
     isort --verbose --check-only --diff --recursive src tests setup.py
 
 [testenv:docs]