diff --git a/django/conf/__init__.py b/django/conf/__init__.py
index 8fff20248f..97f26e9aa3 100644
--- a/django/conf/__init__.py
+++ b/django/conf/__init__.py
@@ -73,6 +73,9 @@ class BaseSettings(object):
         elif name == "ADMIN_MEDIA_PREFIX":
             warnings.warn("The ADMIN_MEDIA_PREFIX setting has been removed; "
                           "use STATIC_URL instead.", DeprecationWarning)
+        elif name == "ALLOWED_INCLUDE_ROOTS" and isinstance(value, basestring):
+            raise ValueError("The ALLOWED_INCLUDE_ROOTS setting must be set "
+                "to a tuple, not a string.")
         object.__setattr__(self, name, value)
 
 
@@ -98,7 +101,8 @@ class Settings(BaseSettings):
         for setting in dir(mod):
             if setting == setting.upper():
                 setting_value = getattr(mod, setting)
-                if setting in tuple_settings and type(setting_value) == str:
+                if setting in tuple_settings and \
+                        isinstance(setting_value, basestring):
                     setting_value = (setting_value,) # In case the user forgot the comma.
                 setattr(self, setting, setting_value)
 
diff --git a/tests/regressiontests/settings_tests/tests.py b/tests/regressiontests/settings_tests/tests.py
index c250aea1ac..3f57fcead2 100644
--- a/tests/regressiontests/settings_tests/tests.py
+++ b/tests/regressiontests/settings_tests/tests.py
@@ -150,6 +150,13 @@ class SettingsTests(TestCase):
     def test_settings_delete_wrapped(self):
         self.assertRaises(TypeError, delattr, settings, '_wrapped')
 
+    def test_allowed_include_roots_string(self):
+        """
+        ALLOWED_INCLUDE_ROOTS is not allowed to be incorrectly set to a string
+        rather than a tuple.
+        """
+        self.assertRaises(ValueError, setattr, settings,
+            'ALLOWED_INCLUDE_ROOTS', '/var/www/ssi/')
 
 
 class TrailingSlashURLTests(TestCase):
diff --git a/tests/regressiontests/templates/tests.py b/tests/regressiontests/templates/tests.py
index d5de05ca09..f74aa757e6 100644
--- a/tests/regressiontests/templates/tests.py
+++ b/tests/regressiontests/templates/tests.py
@@ -425,7 +425,9 @@ class Templates(unittest.TestCase):
 
         #Set ALLOWED_INCLUDE_ROOTS so that ssi works.
         old_allowed_include_roots = settings.ALLOWED_INCLUDE_ROOTS
-        settings.ALLOWED_INCLUDE_ROOTS = os.path.dirname(os.path.abspath(__file__))
+        settings.ALLOWED_INCLUDE_ROOTS = (
+            os.path.dirname(os.path.abspath(__file__)),
+        )
 
         # Warm the URL reversing cache. This ensures we don't pay the cost
         # warming the cache during one of the tests.