diff --git a/django/conf/__init__.py b/django/conf/__init__.py
index f2012a6400..3f707b0897 100644
--- a/django/conf/__init__.py
+++ b/django/conf/__init__.py
@@ -70,6 +70,9 @@ class BaseSettings(object):
         if name in ("MEDIA_URL", "STATIC_URL") and value and not value.endswith('/'):
             warnings.warn('If set, %s must end with a slash' % name,
                           PendingDeprecationWarning)
+        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)
 
 
diff --git a/tests/regressiontests/settings_tests/tests.py b/tests/regressiontests/settings_tests/tests.py
index dc7fde4f2c..37ffd6d577 100644
--- a/tests/regressiontests/settings_tests/tests.py
+++ b/tests/regressiontests/settings_tests/tests.py
@@ -18,6 +18,13 @@ class SettingsTests(unittest.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(unittest.TestCase):
     settings_module = settings
diff --git a/tests/regressiontests/templates/tests.py b/tests/regressiontests/templates/tests.py
index 074852c1c3..d17068821c 100644
--- a/tests/regressiontests/templates/tests.py
+++ b/tests/regressiontests/templates/tests.py
@@ -412,7 +412,9 @@ 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.