diff --git a/tox.ini b/tox.ini
index a0e5acbe66..852de5e6e9 100644
--- a/tox.ini
+++ b/tox.ini
@@ -25,7 +25,7 @@ deps =
         django110: Django>=1.10,<1.11
         django111: Django>=1.11,<2.0
         django20: Django>=2.0,<2.1
-        django21: Django>=2.1a1,<2.2
+        django21: Django>=2.1b1,<2.2
         djangomaster: https://github.com/django/django/archive/master.tar.gz
         -rrequirements/requirements-testing.txt
         -rrequirements/requirements-optionals.txt