diff --git a/Akka.Serialization.MessagePack/Internal/IntIndexedMessagePackFormatterDict.cs b/Akka.Serialization.MessagePack/Internal/IntIndexedMessagePackFormatterDict.cs
index c0eec00..5d2dd6d 100644
--- a/Akka.Serialization.MessagePack/Internal/IntIndexedMessagePackFormatterDict.cs
+++ b/Akka.Serialization.MessagePack/Internal/IntIndexedMessagePackFormatterDict.cs
@@ -32,7 +32,7 @@ public bool TryGet(int i, out IMessagePackFormatter? formatter)
         //which does a full fence and then checks state.
         //Shouldn't happen much and only on startup...
         var f = _formatters;
-        if (i > f.Length)
+        if (i >= f.Length)
         {
             formatter = default;
             return false;