diff --git a/dev-requirements.txt b/dev-requirements.txt
index be19324..7475d00 100644
--- a/dev-requirements.txt
+++ b/dev-requirements.txt
@@ -6,7 +6,7 @@ check-manifest==0.46
 doc8==0.8.1
 flake8-commas==2.0.0
 flake8-quotes==3.2.0
-flake8==3.8.4
+flake8==3.9.0
 freezegun==1.1.0
 isort==5.7.0
 mypy==0.812