diff --git a/keymapper/config.py b/keymapper/config.py
index 2ccff25f..03814e06 100644
--- a/keymapper/config.py
+++ b/keymapper/config.py
@@ -145,17 +145,10 @@ class Config:
     def get(self, key):
         """Read a value from the configuration or get the default."""
         self.check_mtime()
-        if key not in _defaults:
-            logger.error('Unknown setting %s', key)
-            return None
         return self._config.get(key, _defaults[key])
 
     def set(self, key, value):
-        """Write a setting into memory and ~/.config/key-mapper/config."""
-        if key not in _defaults:
-            logger.error('Unknown setting %s', key)
-            return None
-
+        """Write a setting into memory and ~/.config/key-mapper/."""
         self.check_mtime()
 
         if key in self._config and self._config[key] == value:
diff --git a/keymapper/devices.py b/keymapper/devices.py
index bd171932..34632c4d 100644
--- a/keymapper/devices.py
+++ b/keymapper/devices.py
@@ -32,5 +32,10 @@ def find_devices():
 
 
 def get_presets(device):
-    """Get all configured presets for the device"""
+    """Get all configured presets for the device."""
+    pass
+
+
+def get_mappings(device, preset):
+    """Get all configured buttons of the preset."""
     pass
diff --git a/tests/testcases/config.py b/tests/testcases/config.py
index 3164ce67..cee7bf69 100644
--- a/tests/testcases/config.py
+++ b/tests/testcases/config.py
@@ -56,6 +56,12 @@ class ConfigTest(unittest.TestCase):
         get_config('device2', 'preset3', '/tmp/key-mapper')
         self.assertTrue(os.path.isfile('/tmp/key-mapper/device2/preset3'))
 
+        config.set('key1', 'value')
+        config.set('key2', 123)
+        with open('/tmp/key-mapper/device1/preset1', 'r') as f:
+            contents = f.read()
+            self.assertEqual(contents, 'key1=value\nkey2=123\n')
+
 
 if __name__ == "__main__":
     unittest.main()