diff --git a/pex/third_party/__init__.py b/pex/third_party/__init__.py
index d3c14062e..55067c14d 100644
--- a/pex/third_party/__init__.py
+++ b/pex/third_party/__init__.py
@@ -8,10 +8,9 @@
 import os
 import re
 import sys
-
 import warnings
 import zipfile
-from collections import namedtuple, OrderedDict
+from collections import OrderedDict, namedtuple
 
 
 # NB: All pex imports are performed lazily to play well with the un-imports performed by both the
diff --git a/pex/vendor/__init__.py b/pex/vendor/__init__.py
index d331e1d16..3801efc6e 100644
--- a/pex/vendor/__init__.py
+++ b/pex/vendor/__init__.py
@@ -10,7 +10,6 @@
 from pex.orderedset import OrderedSet
 from pex.tracer import TRACER
 
-
 _PACKAGE_COMPONENTS = __name__.split('.')
 
 
diff --git a/tox.ini b/tox.ini
index 3db558683..7eb909956 100644
--- a/tox.ini
+++ b/tox.ini
@@ -128,17 +128,19 @@ commands =
 
 [testenv:isort-run]
 basepython = python2.7
-deps = isort
+deps =
+  isort==4.3.10
 commands =
     isort \
-        -rc \
-        -ns __init__.py \
-        -sg {toxinidir}/pex/vendor/_vendored/** \
+        --recursive \
+        --dont-skip __init__.py \
+        --skip-glob {toxinidir}/pex/vendor/_vendored/** \
         {toxinidir}/pex {toxinidir}/tests
 
 [testenv:isort-check]
 basepython = python2.7
-deps = isort
+deps =
+  {[testenv:isort-run]deps}
 commands = {[testenv:isort-run]commands} -c
 
 [testenv:vendor]