diff --git a/tests/template_tests/filter_tests/test_stringformat.py b/tests/template_tests/filter_tests/test_stringformat.py
index 9501878ebd..9912f50842 100644
--- a/tests/template_tests/filter_tests/test_stringformat.py
+++ b/tests/template_tests/filter_tests/test_stringformat.py
@@ -29,6 +29,11 @@ class FunctionTests(SimpleTestCase):
 
     def test_format(self):
         self.assertEqual(stringformat(1, '03d'), '001')
+        self.assertEqual(stringformat([1, None], 's'), '[1, None]')
+        self.assertEqual(stringformat({1, 2}, 's'), '{1, 2}')
+        self.assertEqual(stringformat({1: 2, 2: 3}, 's'), '{1: 2, 2: 3}')
 
     def test_invalid(self):
         self.assertEqual(stringformat(1, 'z'), '')
+        self.assertEqual(stringformat(object(), 'd'), '')
+        self.assertEqual(stringformat(None, 'd'), '')