diff --git a/amqtt/broker.py b/amqtt/broker.py
index fe949e6..0abc009 100644
--- a/amqtt/broker.py
+++ b/amqtt/broker.py
@@ -692,17 +692,20 @@ class Broker:
         :return:
         """
         returns = await self.plugins_manager.map_plugin_auth(session=session)
-        auth_result = True
-        if returns:
-            for plugin in returns:
-                res = returns[plugin]
-                if res is False:
-                    auth_result = False
-                    self.logger.debug(f"Authentication failed due to '{plugin.__class__}' plugin result: {res}")
-                else:
-                    self.logger.debug(f"'{plugin.__class__}' plugin result: {res}")
-        # If all plugins returned True, authentication is success
-        return auth_result
+
+        results = [ result for _, result in returns.items() if result is not None]
+        if len(results) < 1:
+            self.logger.debug("Authentication failed: no plugin responded with a boolean")
+            return False
+
+        if all(results):
+            self.logger.debug("Authentication succeeded")
+            return True
+
+        for plugin, result in returns.items():
+            self.logger.debug(f"Authentication '{plugin.__class__.__name__}' result: {result}")
+
+        return False
 
     def retain_message(
         self,
diff --git a/tests/plugins/test_sys.py b/tests/plugins/test_sys.py
index 285bee3..234181b 100644
--- a/tests/plugins/test_sys.py
+++ b/tests/plugins/test_sys.py
@@ -79,7 +79,8 @@ async def test_broker_sys_plugin_deprecated_config() -> None:
             match group:
                 case 'tests.mock_plugins':
                     return [
-                            EntryPoint(name='BrokerSysPlugin', group='tests.mock_plugins', value='amqtt.plugins.sys.broker:BrokerSysPlugin'),
+                            EntryPoint(name='broker_sys', group='tests.mock_plugins', value='amqtt.plugins.sys.broker:BrokerSysPlugin'),
+                            EntryPoint(name='auth_anonymous', group='test.mock_plugins', value='amqtt.plugins.sys.auth:AuthAnonymousPlugin'),
                         ]
                 case _:
                     return list()
@@ -91,7 +92,10 @@ async def test_broker_sys_plugin_deprecated_config() -> None:
             "listeners": {
                 "default": {"type": "tcp", "bind": "127.0.0.1:1883", "max_connections": 10},
             },
-            'sys_interval': 1
+            'sys_interval': 1,
+            'auth': {
+                'allow_anonymous': True
+            }
         }
 
         broker = Broker(plugin_namespace='tests.mock_plugins', config=config)
@@ -131,6 +135,7 @@ async def test_broker_sys_plugin_config() -> None:
             "default": {"type": "tcp", "bind": "127.0.0.1:1883", "max_connections": 10},
         },
         'plugins': [
+            {'amqtt.plugins.authentication.AnonymousAuthPlugin': {'allow_anonymous': True}},
             {'amqtt.plugins.sys.broker.BrokerSysPlugin': {'sys_interval': 1}},
         ]
     }