diff --git a/tests/runtests.py b/tests/runtests.py
index 07f2dc7a84..2f9cabb6e5 100755
--- a/tests/runtests.py
+++ b/tests/runtests.py
@@ -19,11 +19,14 @@ from django.test.selenium import SeleniumTestCaseBase
 from django.test.utils import get_runner
 from django.utils import six
 from django.utils._os import upath
-from django.utils.deprecation import RemovedInDjango20Warning
+from django.utils.deprecation import (
+    RemovedInDjango20Warning, RemovedInDjango21Warning,
+)
 from django.utils.log import DEFAULT_LOGGING
 
 # Make deprecation warnings errors to ensure no usage of deprecated features.
 warnings.simplefilter("error", RemovedInDjango20Warning)
+warnings.simplefilter("error", RemovedInDjango21Warning)
 # Make runtime warning errors to ensure no usage of error prone patterns.
 warnings.simplefilter("error", RuntimeWarning)
 # Ignore known warnings in test dependencies.