diff --git a/src/Nullinside.Api.Common/Twitch/TwitchClientProxy.cs b/src/Nullinside.Api.Common/Twitch/TwitchClientProxy.cs
index 1b122a1..bfbea60 100644
--- a/src/Nullinside.Api.Common/Twitch/TwitchClientProxy.cs
+++ b/src/Nullinside.Api.Common/Twitch/TwitchClientProxy.cs
@@ -188,6 +188,7 @@ public async Task AddMessageCallback(string channel, Action<OnMessageReceivedArg
     string channelSan = channel.ToLowerInvariant();
     lock (_onMessageReceived) {
       if (!_onMessageReceived.TryAdd(channelSan, callback)) {
+        _onMessageReceived[channelSan] -= callback;
         _onMessageReceived[channelSan] += callback;
       }
     }