diff --git a/django/test/utils.py b/django/test/utils.py
index 6edd186b54..51ca37e2f0 100644
--- a/django/test/utils.py
+++ b/django/test/utils.py
@@ -6,6 +6,7 @@ from django.core.management import call_command
 from django.dispatch import dispatcher
 from django.test import signals
 from django.template import Template
+from django.utils.translation import deactivate
 
 # The prefix to put on the default database name when creating
 # the test database.
@@ -43,7 +44,7 @@ def setup_test_environment():
 
         - Installing the instrumented test renderer
         - Diverting the email sending functions to a test buffer
-
+        - Setting the active locale to match the LANGUAGE_CODE setting.
     """
     Template.original_render = Template.render
     Template.render = instrumented_test_render
@@ -53,6 +54,8 @@ def setup_test_environment():
 
     mail.outbox = []
 
+    deactivate()
+
 def teardown_test_environment():
     """Perform any global post-test teardown. This involves:
 
diff --git a/tests/runtests.py b/tests/runtests.py
index 736a9a61b3..843850074b 100755
--- a/tests/runtests.py
+++ b/tests/runtests.py
@@ -93,6 +93,7 @@ def django_tests(verbosity, interactive, test_labels):
     old_root_urlconf = settings.ROOT_URLCONF
     old_template_dirs = settings.TEMPLATE_DIRS
     old_use_i18n = settings.USE_I18N
+    old_language_code = settings.LANGUAGE_CODE
     old_middleware_classes = settings.MIDDLEWARE_CLASSES
 
     # Redirect some settings for the duration of these tests.
@@ -100,6 +101,7 @@ def django_tests(verbosity, interactive, test_labels):
     settings.ROOT_URLCONF = 'urls'
     settings.TEMPLATE_DIRS = (os.path.join(os.path.dirname(__file__), TEST_TEMPLATE_DIR),)
     settings.USE_I18N = True
+    settings.LANGUAGE_CODE = 'en'
     settings.MIDDLEWARE_CLASSES = (
         'django.contrib.sessions.middleware.SessionMiddleware',
         'django.contrib.auth.middleware.AuthenticationMiddleware',
@@ -151,6 +153,7 @@ def django_tests(verbosity, interactive, test_labels):
     settings.ROOT_URLCONF = old_root_urlconf
     settings.TEMPLATE_DIRS = old_template_dirs
     settings.USE_I18N = old_use_i18n
+    settings.LANGUAGE_CODE = old_language_code
     settings.MIDDLEWARE_CLASSES = old_middleware_classes
 
 if __name__ == "__main__":