diff --git a/lib/tfw/networking/__init__.py b/lib/tfw/networking/__init__.py
index 3dac2c0..6dd15f9 100644
--- a/lib/tfw/networking/__init__.py
+++ b/lib/tfw/networking/__init__.py
@@ -1,7 +1,7 @@
 # Copyright (C) 2018 Avatao.com Innovative Learning Kft.
 # All Rights Reserved. See LICENSE file for details.
 
-from .serialization import serialize_tfw_msg, deserialize_tfw_msg
+from .serialization import serialize_tfw_msg, deserialize_tfw_msg, validate_message
 from .zmq_connector_base import ZMQConnectorBase
 # from .controller_connector import ControllerConnector # TODO: readd once controller stuff is resolved
 from .message_sender import MessageSender
diff --git a/lib/tfw/networking/serialization.py b/lib/tfw/networking/serialization.py
index f24b38a..0586309 100644
--- a/lib/tfw/networking/serialization.py
+++ b/lib/tfw/networking/serialization.py
@@ -24,6 +24,12 @@ The purpose of this module is abstracting away this low level behaviour.
 import json
 
 
+def validate_message(message):
+    if 'key' not in message:
+        return False
+    return True
+
+
 def serialize_tfw_msg(message):
     return _serialize_all(message['key'], message)
 
diff --git a/lib/tfw/networking/server/zmq_websocket_handler.py b/lib/tfw/networking/server/zmq_websocket_handler.py
index 4d0d994..fee2ff1 100644
--- a/lib/tfw/networking/server/zmq_websocket_handler.py
+++ b/lib/tfw/networking/server/zmq_websocket_handler.py
@@ -6,7 +6,7 @@ from abc import ABC, abstractmethod
 
 from tornado.websocket import WebSocketHandler
 
-from tfw.networking import deserialize_tfw_msg
+from tfw.networking import deserialize_tfw_msg, validate_message
 from tfw.config.logs import logging
 
 LOG = logging.getLogger(__name__)
@@ -32,15 +32,17 @@ class ZMQWebSocketHandler(WebSocketHandler, ABC):
         keyhandlers = {'mirror': self.mirror}
 
         message = deserialize_tfw_msg(*msg_parts)
-        key = message['key']
         LOG.debug('Received on pull socket: %s', message)
+        if not validate_message(message):
+            return
+
         self.handle_trigger(message)
-        if key not in keyhandlers:
+        if message['key'] not in keyhandlers:
             for instance in ZMQWebSocketHandler.instances:
                 instance.write_message(message)
         else:
             try:
-                keyhandlers[key](message)
+                keyhandlers[message['key']](message)
             except KeyError:
                 LOG.error('Invalid mirror message format! Ignoring.')
 
@@ -50,7 +52,8 @@ class ZMQWebSocketHandler(WebSocketHandler, ABC):
 
     def on_message(self, message):
         LOG.debug('Received on WebSocket: %s', message)
-        self.send_message(self.make_eventhandler_response(message))
+        if validate_message(message):
+            self.send_message(self.make_eventhandler_response(message))
 
     @abstractmethod
     def make_eventhandler_response(self, message):