diff --git a/reclass/datatypes/tests/test_parameters.py b/reclass/datatypes/tests/test_parameters.py
index 577bdc4..5c91893 100644
--- a/reclass/datatypes/tests/test_parameters.py
+++ b/reclass/datatypes/tests/test_parameters.py
@@ -202,6 +202,15 @@
         p1.initialise_interpolation()
         self.assertEqual(p1.as_dict()['key'], None)
 
+    def test_merge_none_over_list_negative(self):
+        l = ['foo', 1, 2]
+        settings = Settings({'allow_none_override': False})
+        p1 = Parameters(dict(key=l[:2]), settings, '')
+        p2 = Parameters(dict(key=None), settings, '')
+        with self.assertRaises(TypeError):
+            p1.merge(p2)
+            p1.initialise_interpolation()
+
     def test_merge_none_over_dict(self):
         settings = Settings({'allow_none_override': True})
         p1 = Parameters(dict(key=SIMPLE), settings, '')
@@ -210,6 +219,14 @@
         p1.initialise_interpolation()
         self.assertEqual(p1.as_dict()['key'], None)
 
+    def test_merge_none_over_dict_negative(self):
+        settings = Settings({'allow_none_override': False})
+        p1 = Parameters(dict(key=SIMPLE), settings, '')
+        p2 = Parameters(dict(key=None), settings, '')
+        with self.assertRaises(TypeError):
+            p1.merge(p2)
+            p1.initialise_interpolation()
+
     # def test_merge_bare_dict_over_dict(self):
         # settings = Settings({'allow_bare_override': True})
         # p1 = Parameters(dict(key=SIMPLE), settings, '')
diff --git a/reclass/defaults.py b/reclass/defaults.py
index 980bb92..a07877d 100644
--- a/reclass/defaults.py
+++ b/reclass/defaults.py
@@ -29,7 +29,7 @@
 OPT_ALLOW_SCALAR_OVER_LIST = False
 OPT_ALLOW_LIST_OVER_SCALAR = False
 OPT_ALLOW_DICT_OVER_SCALAR = False
-OPT_ALLOW_NONE_OVERRIDE = True
+OPT_ALLOW_NONE_OVERRIDE = False
 
 OPT_INVENTORY_IGNORE_FAILED_NODE = False
 OPT_INVENTORY_IGNORE_FAILED_RENDER = False
diff --git a/reclass/values/scaitem.py b/reclass/values/scaitem.py
index 466d3c9..6bd65dc 100644
--- a/reclass/values/scaitem.py
+++ b/reclass/values/scaitem.py
@@ -21,12 +21,12 @@
         if item.type == Item.SCALAR:
             return self
         elif item.type == Item.LIST:
-            if self._settings.allow_scalar_over_list or (self._settings.allow_none_override and self._value in [None, 'none', 'None']):
+            if self._settings.allow_scalar_over_list or (self._settings.allow_none_override and self._value is None):
                 return self
             else:
                 raise TypeError('allow scalar over list = False: cannot merge %s over %s' % (repr(self), repr(item)))
         elif item.type == Item.DICTIONARY:
-            if self._settings.allow_scalar_over_dict or (self._settings.allow_none_override and self._value in [None, 'none', 'None']):
+            if self._settings.allow_scalar_over_dict or (self._settings.allow_none_override and self._value is None):
                 return self
             else:
                 raise TypeError('allow scalar over dict = False: cannot merge %s over %s' % (repr(self), repr(item)))