diff --git a/dev_requirements.txt b/dev_requirements.txt
--- a/dev_requirements.txt
+++ b/dev_requirements.txt
@@ -6,3 +6,4 @@ mock >= 3.0.0, < 4.1
 Sphinx >= 1.8.0, < 2.4
 WebTest >= 2.0.6, < 2.1
 isort == 4.3.21
+pyflakes == 2.1.1