diff --git a/tox.ini b/tox.ini
index 3344539fc6..a5d1697e8a 100644
--- a/tox.ini
+++ b/tox.ini
@@ -52,6 +52,12 @@ envlist =
     ; Only officially supported Python versions are tested for each Django
     ; major release. Updated list can be found at:
     ; https://docs.djangoproject.com/en/dev/faq/install/#what-python-version-can-i-use-with-django
+    ; The numbers at the end of the environment names
+    ; below mean these dependencies are being used:
+    ; 0: django~=2.0
+    ; 1: django~=3.0
+    ; 2: django>=4.0b1,<5.0 backports.zoneinfo==0.2.1
+    ; 3: django>=4.0b1,<5.0
     py3{8,9}-test-instrumentation-django-0
     py3{8,9}-test-instrumentation-django-1
     py3{8,9}-test-instrumentation-django-2