diff --git a/django/forms/formsets.py b/django/forms/formsets.py
index 58af0ac23b8..7acf238795b 100644
--- a/django/forms/formsets.py
+++ b/django/forms/formsets.py
@@ -271,7 +271,7 @@ class BaseFormSet(StrAndUnicode):
         try:
             self.clean()
         except ValidationError, e:
-            self._non_form_errors = e.messages
+            self._non_form_errors = self.error_class(e.messages)
 
     def clean(self):
         """
diff --git a/tests/regressiontests/admin_views/tests.py b/tests/regressiontests/admin_views/tests.py
index 199b41afcb9..911549fa066 100644
--- a/tests/regressiontests/admin_views/tests.py
+++ b/tests/regressiontests/admin_views/tests.py
@@ -11,6 +11,7 @@ from django.contrib.admin.models import LogEntry, DELETION
 from django.contrib.admin.sites import LOGIN_FORM_KEY
 from django.contrib.admin.util import quote
 from django.contrib.admin.helpers import ACTION_CHECKBOX_NAME
+from django.forms.util import ErrorList
 from django.utils import formats
 from django.utils.cache import get_max_age
 from django.utils.html import escape
@@ -1028,6 +1029,22 @@ class AdminViewListEditable(TestCase):
         response = self.client.post('/test_admin/admin/admin_views/person/', data)
         self.assertContains(response, "Grace is not a Zombie")
 
+    def test_non_form_errors_is_errorlist(self):
+        # test if non-form errors are correctly handled; ticket #12878
+        data = {
+            "form-TOTAL_FORMS": "1",
+            "form-INITIAL_FORMS": "1",
+            "form-MAX_NUM_FORMS": "0",
+
+            "form-0-id": "2",
+            "form-0-alive": "1",
+            "form-0-gender": "2",
+        }
+        response = self.client.post('/test_admin/admin/admin_views/person/', data)
+        non_form_errors = response.context['cl'].formset.non_form_errors()
+        self.assert_(isinstance(non_form_errors, ErrorList))
+        self.assertEqual(str(non_form_errors), str(ErrorList(["Grace is not a Zombie"])))
+
     def test_list_editable_ordering(self):
         collector = Collector.objects.create(id=1, name="Frederick Clegg")
 
diff --git a/tests/regressiontests/forms/formsets.py b/tests/regressiontests/forms/formsets.py
index 700ab7c358b..d9d4082f715 100644
--- a/tests/regressiontests/forms/formsets.py
+++ b/tests/regressiontests/forms/formsets.py
@@ -621,4 +621,20 @@ Make sure the management form has the correct prefix.
 >>> formset.management_form.prefix
 'form'
 
+# Regression test for #12878 #################################################
+
+>>> data = {
+...     'drinks-TOTAL_FORMS': '2', # the number of forms rendered
+...     'drinks-INITIAL_FORMS': '0', # the number of forms with initial data
+...     'drinks-MAX_NUM_FORMS': '0', # max number of forms
+...     'drinks-0-name': 'Gin and Tonic',
+...     'drinks-1-name': 'Gin and Tonic',
+... }
+
+>>> formset = FavoriteDrinksFormSet(data, prefix='drinks')
+>>> formset.is_valid()
+False
+>>> print formset.non_form_errors()
+<ul class="errorlist"><li>You may only specify a drink once.</li></ul>
+
 """