diff --git a/tools/requirements.txt b/tools/requirements.txt
index c48971c5..f1bafe50 100644
--- a/tools/requirements.txt
+++ b/tools/requirements.txt
@@ -7,7 +7,7 @@ contextlib2==0.6.0.post1 ; python_version < '3'
 coverage==5.0.2
 entrypoints==0.3
 enum34==1.1.6
-flake8==3.7.9
+flake8==3.9.1
 funcsigs==1.0.2 ; python_version < '3.3'
 functools32==3.2.3.post2 ; python_version < '3'
 futures==3.3.0 ; python_version < '3.2'