diff --git a/requirements-dev.txt b/requirements-dev.txt
index cd93f2433..35c57769a 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -4,7 +4,7 @@
 -r requirements-hyperopt.txt
 
 coveralls==3.0.1
-flake8==3.9.0
+flake8==3.9.1
 flake8-type-annotations==0.1.0
 flake8-tidy-imports==4.2.1
 mypy==0.812