diff --git a/modules/libpref/init/generate_static_pref_list.py b/modules/libpref/init/generate_static_pref_list.py
index d2f5bda056f1..5242c12214bc 100644
--- a/modules/libpref/init/generate_static_pref_list.py
+++ b/modules/libpref/init/generate_static_pref_list.py
@@ -3,14 +3,16 @@
 # You can obtain one at http://mozilla.org/MPL/2.0/.
 
 from __future__ import print_function
-import buildconfig
-from collections import defaultdict
+
 import os
-from six import StringIO
 import sys
+from collections import defaultdict
+
+import buildconfig
 import yaml
 from mozbuild.preprocessor import Preprocessor
-from mozbuild.util import ensureParentDir, FileAvoidWrite
+from mozbuild.util import FileAvoidWrite, ensureParentDir
+from six import StringIO
 
 VALID_KEYS = {
     "name",
diff --git a/modules/libpref/test/test_generate_static_pref_list.py b/modules/libpref/test/test_generate_static_pref_list.py
index ee28af1cb855..6fa7104c4704 100644
--- a/modules/libpref/test/test_generate_static_pref_list.py
+++ b/modules/libpref/test/test_generate_static_pref_list.py
@@ -4,13 +4,14 @@
 
 from __future__ import absolute_import, print_function
 
-import mozpack.path as mozpath
-import mozunit
 import sys
 import unittest
-import yaml
 from os import path
 
+import mozpack.path as mozpath
+import mozunit
+import yaml
+
 try:
     from StringIO import StringIO
 except ImportError: