diff --git a/tox.ini b/tox.ini
index 1ffa639d..fa17049c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -17,7 +17,7 @@ deps =
     flake8
     Jinja2
     mock
-    pytest
+    pytest==3.6.4
     pytest-asyncio
     pytest-cov
     pytest-mock