diff --git a/requirements.txt b/requirements.txt
index da91ff3..025b201 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,5 @@
 devpi-client>=3.0.0
-flake8
+flake8==3.5.0
 pytest-runner
 pytest-cov
 pytest-mock