diff --git a/requirements/constraints.txt b/requirements/constraints.txt
index a01f177..fb267bd 100644
--- a/requirements/constraints.txt
+++ b/requirements/constraints.txt
@@ -21,4 +21,7 @@ django-filter<24.1
 djangorestframework<3.15.2
 
 # Latest version compatible with Django 3.2
-django-oauth-toolkit==2.4.0
\ No newline at end of file
+django-oauth-toolkit==2.4.0
+
+# backports.zoneinfo is only needed for Python < 3.9
+backports.zoneinfo; python_version<'3.9'