diff --git a/i3pystatus/core/settings.py b/i3pystatus/core/settings.py
index 75095e8..e84fd3f 100644
--- a/i3pystatus/core/settings.py
+++ b/i3pystatus/core/settings.py
@@ -30,11 +30,13 @@ class SettingsBaseMeta(type):
             settings += tuple(getattr(base, "settings", []))
             required |= set(getattr(base, "required", []))
         # if a derived class defines a default for a setting it is not
-        # required anymore.
+        # required anymore, provided that default is not set to None.
         for base in inspect.getmro(cls):
             for r in list(required):
-                if hasattr(base, r):
+                if hasattr(base, r) and getattr(base, r) != getattr(cls, r) \
+                        or hasattr(cls, r) and getattr(cls, r) is not None:
                     required.remove(r)
+
         return unique(settings), required
 
 
diff --git a/tests/test_core_modules.py b/tests/test_core_modules.py
index 0ca7897..3d838fe 100644
--- a/tests/test_core_modules.py
+++ b/tests/test_core_modules.py
@@ -2,9 +2,9 @@ import time
 from unittest.mock import MagicMock
 
 import pytest
-
 from i3pystatus import IntervalModule
-from i3pystatus.core.modules import is_method_of
+from i3pystatus.core.exceptions import ConfigMissingError
+from i3pystatus.core.modules import is_method_of, Module
 
 left_click = 1
 right_click = 3
@@ -145,3 +145,66 @@ def test_is_method_of():
         assert not is_method_of(source_object.assigned_function, object)
         assert not is_method_of(source_object.member, object)
         assert not is_method_of(source_object.string_member, object)
+
+
+def test_required_raises():
+    """ Ensure undefined required settings raise a ConfigMissingError """
+
+    class TestRequired(Module):
+        settings = (
+            ("some_setting",),
+        )
+        required = ('some_setting',)
+
+    with pytest.raises(ConfigMissingError):
+        TestRequired()
+
+    TestRequired(some_setting='foo')
+
+
+def test_required_defined_raises():
+    """ Ensure defined but unmodified required settings raise a ConfigMissingError """
+
+    class TestRequiredDefined(Module):
+        settings = (
+            ("some_setting",),
+        )
+        required = ('some_setting',)
+        some_setting = None
+
+    with pytest.raises(ConfigMissingError):
+        TestRequiredDefined()
+
+    TestRequiredDefined(some_setting='foo')
+
+
+def test_required_subclass_none_raises():
+    """ Ensure required settings defined in subclasses raise a ConfigMissingError if they are set to None"""
+
+    class TestRequiredDefined(Module):
+        settings = (
+            ("some_setting",),
+        )
+        required = ('some_setting',)
+
+    class TestSubClass(TestRequiredDefined):
+        some_setting = None
+
+    with pytest.raises(ConfigMissingError):
+        TestRequiredDefined()
+    TestSubClass(some_setting='foo')
+
+
+def test_required_subclass_overide():
+    """ Ensure required settings defined in subclasses do not raise a ConfigMissingError """
+
+    class TestRequiredDefined(Module):
+        settings = (
+            ("some_setting",),
+        )
+        required = ('some_setting',)
+
+    class TestSubClass(TestRequiredDefined):
+        some_setting = 'foo'
+
+    TestSubClass()