diff --git a/requirements/integration.txt b/requirements/integration.txt
index 1395383..3391511 100644
--- a/requirements/integration.txt
+++ b/requirements/integration.txt
@@ -18,6 +18,7 @@ flake8-docstrings
 flake8-builtins
 flake8-comprehensions
 flake8-junit-report
+flake8-2020
 pylint-ignore>=2020.1013
 mypy
 # pylint doesn't support isort>=5 for now
diff --git a/setup.cfg b/setup.cfg
index ad0eff8..4e9f261 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -75,7 +75,7 @@ ignore =
     D400
     # First line should be in imperative mood
     D401
-select = A,AAA,D,C,E,F,W,H,B,D212,D404,D405,D406,B901,B950
+select = A,AAA,D,C,E,F,W,H,B,D212,D404,D405,D406,B901,B950,YTT
 exclude =
     .git
     __pycache__
diff --git a/src/pycalver/pysix.py b/src/pycalver/pysix.py
index 354f2d5..f11c7d8 100644
--- a/src/pycalver/pysix.py
+++ b/src/pycalver/pysix.py
@@ -6,7 +6,7 @@
 import sys
 import typing as typ
 
-PY2 = sys.version < "3"
+PY2 = sys.version_info.major < 3
 
 
 try: