diff --git a/requirements.txt b/requirements.txt
index b3ea4c6..d0baef6 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,9 +1,9 @@
 # Testing
 django-oscar>=2.0,<3.2
 django-webtest==1.9.10
-tox>=3.20<4
+tox>=3.20,<4
 pytest-django==4.5.2
-pytest-cov>=2.10<3
+pytest-cov>=2.10,<3
 django-widget-tweaks==1.4.9
 sorl-thumbnail
 coverage