diff --git a/Source/Coinbase.Pro/WebSockets/CoinbaseProWebSocket.cs b/Source/Coinbase.Pro/WebSockets/CoinbaseProWebSocket.cs
index 9f54aeb..9f0e22a 100644
--- a/Source/Coinbase.Pro/WebSockets/CoinbaseProWebSocket.cs
+++ b/Source/Coinbase.Pro/WebSockets/CoinbaseProWebSocket.cs
@@ -132,7 +132,7 @@ public async Task SubscribeAsync(Subscription subscription)
 
       public void Unsubscribe(Subscription subscription)
       {
-         subscription.ExtraJson.Add("type", JToken.FromObject(MessageType.Unsubscribe));
+         subscription.ExtraJson["type"] = JToken.FromObject(MessageType.Unsubscribe);
 
          var json = JsonConvert.SerializeObject(subscription);