diff --git a/requirements.txt b/requirements.txt
index f65d4563..02842d2d 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -12,7 +12,7 @@ flake8-isort==4.0.0
 # Testing
 # ------------------------------------------------------------------------------
 tox==3.20.1
-pytest==5.4.3
+pytest==5.4.3  # pyup: <6  # https://github.com/hackebrot/pytest-cookies/issues/51
 pytest-cookies==0.5.1
 pytest-instafail==0.4.2
 pyyaml==5.3.1