diff --git a/ably/realtime/connection.py b/ably/realtime/connection.py
index d5c79f0d..179e4a6b 100644
--- a/ably/realtime/connection.py
+++ b/ably/realtime/connection.py
@@ -17,6 +17,11 @@ class ConnectionState(Enum):
     FAILED = 'failed'
 
 
+class ProtocolMessageAction(Enum):
+    CONNECTED = 4
+    ERROR = 9
+
+
 class RealtimeConnection:
     def __init__(self, realtime):
         self.options = realtime.options
@@ -60,13 +65,13 @@ async def ws_read_loop(self):
             raw = await self.__websocket.recv()
             msg = json.loads(raw)
             action = msg['action']
-            if action == 4:  # CONNECTED
+            if action == ProtocolMessageAction.CONNECTED:  # CONNECTED
                 if self.__connected_future:
                     self.__connected_future.set_result(None)
                     self.__connected_future = None
                 else:
-                    log.warn('CONNECTED message receieved but connected_future not set')
-            if action == 9:  # ERROR
+                    log.warn('CONNECTED message received but connected_future not set')
+            if action == ProtocolMessageAction.ERROR:  # ERROR
                 error = msg["error"]
                 if error['nonfatal'] is False:
                     self.__state = ConnectionState.FAILED
diff --git a/ably/realtime/realtime.py b/ably/realtime/realtime.py
index 36cf1cbe..de70e41c 100644
--- a/ably/realtime/realtime.py
+++ b/ably/realtime/realtime.py
@@ -21,7 +21,7 @@ def __init__(self, key=None, **kwargs):
         if key is not None:
             options = Options(key=key, **kwargs)
         else:
-            raise ValueError("Key is missing. Provide an API key")
+            raise ValueError("Key is missing. Provide an API key.")
 
         self.__auth = Auth(self, options)
         self.__options = options