diff --git a/mitmproxy/addons/proxyserver.py b/mitmproxy/addons/proxyserver.py
index 244df343e..e89f9c5a1 100644
--- a/mitmproxy/addons/proxyserver.py
+++ b/mitmproxy/addons/proxyserver.py
@@ -157,7 +157,7 @@ class Proxyserver:
             if isinstance(f, http.HTTPFlow):
                 if f.websocket:
                     event = WebSocketMessageInjected(
-                        f.client_conn if from_client else f.server_conn,
+                        f,
                         websocket.WebSocketMessage(
                             Opcode.TEXT, from_client, message.encode()
                         )
diff --git a/mitmproxy/proxy/events.py b/mitmproxy/proxy/events.py
index 4593d9d49..1b6b6ea02 100644
--- a/mitmproxy/proxy/events.py
+++ b/mitmproxy/proxy/events.py
@@ -8,6 +8,7 @@ import typing
 import warnings
 from dataclasses import dataclass, is_dataclass
 
+from mitmproxy import flow
 from mitmproxy.proxy import commands
 from mitmproxy.connection import Connection
 
@@ -112,8 +113,9 @@ T = typing.TypeVar('T')
 
 
 @dataclass
-class MessageInjected(ConnectionEvent, typing.Generic[T]):
+class MessageInjected(Event, typing.Generic[T]):
     """
     The user has injected a custom WebSocket/TCP/... message.
     """
+    flow: flow.Flow
     message: T
diff --git a/mitmproxy/proxy/layers/http/__init__.py b/mitmproxy/proxy/layers/http/__init__.py
index a0a7682ea..78606b21e 100644
--- a/mitmproxy/proxy/layers/http/__init__.py
+++ b/mitmproxy/proxy/layers/http/__init__.py
@@ -589,10 +589,8 @@ class HttpLayer(layer.Layer):
             yield from self.event_to_child(stream, event)
         elif isinstance(event, events.MessageInjected):
             # For injected messages we pass the HTTP stacks entirely and directly address the stream.
-            conn = self.connections[event.connection]
-            if isinstance(conn, Http1Server):
-                stream_id = conn.stream_id
-            elif isinstance(conn, HttpStream):
+            conn = self.connections[event.flow.server_conn]
+            if isinstance(conn, HttpStream):
                 stream_id = conn.stream_id
             else:
                 # We reach to the end of the connection's child stack to get the HTTP/1 client layer,
diff --git a/mitmproxy/proxy/layers/websocket.py b/mitmproxy/proxy/layers/websocket.py
index 328ad34ee..f55ab07d6 100644
--- a/mitmproxy/proxy/layers/websocket.py
+++ b/mitmproxy/proxy/layers/websocket.py
@@ -128,10 +128,16 @@ class WebsocketLayer(layer.Layer):
     _handle_event = start
 
     @expect(events.DataReceived, events.ConnectionClosed, WebSocketMessageInjected)
-    def relay_messages(self, event: events.ConnectionEvent) -> layer.CommandGenerator[None]:
+    def relay_messages(self, event: events.Event) -> layer.CommandGenerator[None]:
         assert self.flow.websocket  # satisfy type checker
 
-        from_client = event.connection == self.context.client
+        if isinstance(event, events.ConnectionEvent):
+            from_client = event.connection == self.context.client
+        elif isinstance(event, WebSocketMessageInjected):
+            from_client = event.message.from_client
+        else:
+            raise AssertionError(f"Unexpected event: {event}")
+
         from_str = 'client' if from_client else 'server'
         if from_client:
             src_ws = self.client_ws
diff --git a/test/mitmproxy/addons/test_proxyserver.py b/test/mitmproxy/addons/test_proxyserver.py
index 049008211..d71b23615 100644
--- a/test/mitmproxy/addons/test_proxyserver.py
+++ b/test/mitmproxy/addons/test_proxyserver.py
@@ -56,10 +56,10 @@ async def test_start_stop():
 
             proxy_addr = ps.server.sockets[0].getsockname()[:2]
             reader, writer = await asyncio.open_connection(*proxy_addr)
-            assert repr(ps) == "ProxyServer(running, 1 active conns)"
             req = f"GET http://{addr[0]}:{addr[1]}/hello HTTP/1.1\r\n\r\n"
             writer.write(req.encode())
             assert await reader.readuntil(b"\r\n\r\n") == b"HTTP/1.1 204 No Content\r\n\r\n"
+            assert repr(ps) == "ProxyServer(running, 1 active conns)"
 
             tctx.configure(ps, server=False)
             await tctx.master.await_log("Stopping server", level="info")
diff --git a/test/mitmproxy/proxy/layers/test_websocket.py b/test/mitmproxy/proxy/layers/test_websocket.py
index 9b4ceb660..7e3ef5cd8 100644
--- a/test/mitmproxy/proxy/layers/test_websocket.py
+++ b/test/mitmproxy/proxy/layers/test_websocket.py
@@ -328,7 +328,7 @@ def test_inject_message(ws_testdata):
             playbook
             << websocket.WebsocketStartHook(flow)
             >> reply()
-            >> WebSocketMessageInjected(tctx.server, WebSocketMessage(Opcode.TEXT, False, b"hello"))
+            >> WebSocketMessageInjected(flow, WebSocketMessage(Opcode.TEXT, False, b"hello"))
             << websocket.WebsocketMessageHook(flow)
     )
     assert flow.websocket.messages[-1].content == b"hello"