diff --git a/src/socketio/async_server.py b/src/socketio/async_server.py
index 5f51844..f10fb8a 100644
--- a/src/socketio/async_server.py
+++ b/src/socketio/async_server.py
@@ -584,7 +584,7 @@ class AsyncServer(base_server.BaseServer):
             return
         self.manager.pre_disconnect(sid, namespace=namespace)
         await self._trigger_event('disconnect', namespace, sid,
-                                  reason or self.reason.UNKNOWN)
+                                  reason or self.reason.CLIENT_DISCONNECT)
         await self.manager.disconnect(sid, namespace, ignore_queue=True)
 
     async def _handle_event(self, eio_sid, namespace, id, data):
diff --git a/src/socketio/server.py b/src/socketio/server.py
index 21a6de4..71c702d 100644
--- a/src/socketio/server.py
+++ b/src/socketio/server.py
@@ -566,7 +566,7 @@ class Server(base_server.BaseServer):
             return
         self.manager.pre_disconnect(sid, namespace=namespace)
         self._trigger_event('disconnect', namespace, sid,
-                            reason or self.reason.UNKNOWN)
+                            reason or self.reason.CLIENT_DISCONNECT)
         self.manager.disconnect(sid, namespace, ignore_queue=True)
 
     def _handle_event(self, eio_sid, namespace, id, data):
diff --git a/tests/async/test_namespace.py b/tests/async/test_namespace.py
index 656cb47..526d676 100644
--- a/tests/async/test_namespace.py
+++ b/tests/async/test_namespace.py
@@ -25,10 +25,10 @@ class TestAsyncNamespace:
 
         ns = MyNamespace('/foo')
         ns._set_server(mock.MagicMock())
-        _run(ns.trigger_event('disconnect', 'sid', 'foo'))
+        await ns.trigger_event('disconnect', 'sid', 'foo')
         assert result['result'] == ('sid', 'foo')
 
-    def test_legacy_disconnect_event(self):
+    async def test_legacy_disconnect_event(self):
         result = {}
 
         class MyNamespace(async_namespace.AsyncNamespace):
@@ -37,10 +37,10 @@ class TestAsyncNamespace:
 
         ns = MyNamespace('/foo')
         ns._set_server(mock.MagicMock())
-        _run(ns.trigger_event('disconnect', 'sid', 'foo'))
+        await ns.trigger_event('disconnect', 'sid', 'foo')
         assert result['result'] == 'sid'
 
-    def test_legacy_disconnect_event_async(self):
+    async def test_legacy_disconnect_event_async(self):
         result = {}
 
         class MyNamespace(async_namespace.AsyncNamespace):
@@ -266,7 +266,7 @@ class TestAsyncNamespace:
         await ns.disconnect('sid', namespace='/bar')
         ns.server.disconnect.assert_awaited_with('sid', namespace='/bar')
 
-    async def test_disconnect_event(self):
+    async def test_disconnect_event_client(self):
         result = {}
 
         class MyNamespace(async_namespace.AsyncClientNamespace):
diff --git a/tests/async/test_server.py b/tests/async/test_server.py
index 34b6c38..f60de27 100644
--- a/tests/async/test_server.py
+++ b/tests/async/test_server.py
@@ -653,7 +653,8 @@ class TestAsyncServer:
         await s._handle_eio_message('123', '2/bar,["msg","a","b"]')
         await s._handle_eio_message('123', '2/foo,["my message","a","b","c"]')
         await s._handle_eio_message('123', '2/bar,["my message","a","b","c"]')
-        await s._trigger_event('disconnect', '/bar', sid_bar, s.reason.UNKNOWN)
+        await s._trigger_event('disconnect', '/bar', sid_bar,
+                               s.reason.CLIENT_DISCONNECT)
         connect_star_handler.assert_called_once_with('/bar', sid_bar)
         msg_foo_handler.assert_called_once_with(sid_foo, 'a', 'b')
         msg_star_handler.assert_called_once_with('/bar', sid_bar, 'a', 'b')
diff --git a/tests/common/test_namespace.py b/tests/common/test_namespace.py
index be6bccb..f1476e4 100644
--- a/tests/common/test_namespace.py
+++ b/tests/common/test_namespace.py
@@ -252,7 +252,6 @@ class TestNamespace:
         ns.trigger_event('disconnect', 'foo')
         assert result['result'] == 'ok'
 
-
     def test_event_not_found_client(self):
         result = {}
 
diff --git a/tests/common/test_server.py b/tests/common/test_server.py
index 5ba119a..445d5d9 100644
--- a/tests/common/test_server.py
+++ b/tests/common/test_server.py
@@ -610,7 +610,8 @@ class TestServer:
         s._handle_eio_message('123', '2/bar,["msg","a","b"]')
         s._handle_eio_message('123', '2/foo,["my message","a","b","c"]')
         s._handle_eio_message('123', '2/bar,["my message","a","b","c"]')
-        s._trigger_event('disconnect', '/bar', sid_bar, s.reason.UNKNOWN)
+        s._trigger_event('disconnect', '/bar', sid_bar,
+                         s.reason.CLIENT_DISCONNECT)
         connect_star_handler.assert_called_once_with('/bar', sid_bar)
         msg_foo_handler.assert_called_once_with(sid_foo, 'a', 'b')
         msg_star_handler.assert_called_once_with('/bar', sid_bar, 'a', 'b')