diff --git a/osprofiler/_utils.py b/osprofiler/_utils.py
index f0c053b..4f839b6 100644
--- a/osprofiler/_utils.py
+++ b/osprofiler/_utils.py
@@ -29,8 +29,10 @@ except (AttributeError, ImportError):
     # Taken/slightly modified from:
     # https://mail.python.org/pipermail/python-checkins/2012-June/114532.html
     def compare_digest(a, b):
-        """Returns the equivalent of 'a == b', but avoids content based short
-        circuiting to reduce the vulnerability to timing attacks.
+        """Returns the equivalent of 'a == b'.
+
+        This method avoids content based short circuiting to reduce the
+        vulnerability to timing attacks.
         """
         # We assume the length of the expected digest is public knowledge,
         # thus this early return isn't leaking anything an attacker wouldn't
diff --git a/requirements.txt b/requirements.txt
index 16b03c1..cc50321 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,3 @@
 argparse
-six>=1.7.0
+six>=1.9.0
 WebOb>=1.2.3
diff --git a/test-requirements.txt b/test-requirements.txt
index c378c04..8ba925b 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -1,11 +1,11 @@
-hacking>=0.8.0,<0.9
+hacking>=0.10.2,<0.11
 
 coverage>=3.6
 discover
-mock>=1.0
+mock>=1.2
 python-subunit>=0.0.18
 testrepository>=0.0.18
-testtools>=0.9.34
+testtools>=1.4.0
 
-oslosphinx
-sphinx>=1.1.2,!=1.2.0,<1.3
+oslosphinx>=2.5.0,!=3.4.0  # Apache-2.0
+sphinx>=1.1.2,!=1.2.0,!=1.3b1,<1.3
diff --git a/tests/cmd/test_shell.py b/tests/cmd/test_shell.py
index f372762..e2e76ab 100644
--- a/tests/cmd/test_shell.py
+++ b/tests/cmd/test_shell.py
@@ -188,7 +188,7 @@ class ShellTestCase(test.TestCase):
                 "started": 0, "finished": 0, "name": "total"}, "children": []}
         mock_notifications.return_value = notifications
 
-        #NOTE(akurilin): to simplify assert statement, html-template should be
+        # NOTE(akurilin): to simplify assert statement, html-template should be
         # replaced.
         html_template = (
             "A long time ago in a galaxy far, far away..."