diff --git a/requirements.txt b/requirements.txt
index 725cc5010..c98ec18c4 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,6 +2,7 @@ autopep8==1.3.3
 cffi==1.11.4
 click==6.7
 emoji==0.4.5
+flake8==3.5.0
 Flask==0.12.2
 Flask-OAuth==0.12
 gunicorn==19.7.1