diff --git a/examples/addons/websocket-inject-message.py b/examples/addons/websocket-inject-message.py
new file mode 100644
index 000000000..012d4b27e
--- /dev/null
+++ b/examples/addons/websocket-inject-message.py
@@ -0,0 +1,31 @@
+"""
+Inject a WebSocket message into a running connection.
+
+This example shows how to inject a WebSocket message into a running connection.
+"""
+import asyncio
+
+from mitmproxy import ctx, http
+
+
+# Simple example: Inject a message as a response to an event
+
+def websocket_message(flow):
+    last_message = flow.websocket.messages[-1]
+    if b"secret" in last_message.content:
+        last_message.kill()
+        ctx.master.commands.call("inject", [flow], not last_message.from_client, "ssssssh")
+
+
+# Complex example: Schedule a periodic timer
+
+async def inject_async(flow: http.HTTPFlow):
+    msg = "hello from mitmproxy! "
+    while flow.server_conn.connected:
+        ctx.master.commands.call("inject", [flow], False, msg)
+        await asyncio.sleep(1)
+        msg = msg[1:] + msg[:1]
+
+
+def websocket_start(flow: http.HTTPFlow):
+    asyncio.create_task(inject_async(flow))
diff --git a/mitmproxy/addons/proxyserver.py b/mitmproxy/addons/proxyserver.py
index 3922c4826..9ec1c176a 100644
--- a/mitmproxy/addons/proxyserver.py
+++ b/mitmproxy/addons/proxyserver.py
@@ -168,6 +168,7 @@ class Proxyserver:
                 event = TcpMessageInjected(f, tcp.TCPMessage(from_client, message_bytes))
             else:  # pragma: no cover
                 ctx.log.warn(f"Cannot inject message into {f.__class__.__name__}, skipping.")
+                continue
 
             try:
                 self.inject_event(f, event)