diff --git a/Modspec.Model/IModbusClient.cs b/Modspec.Model/IModbusClient.cs
index bf487fa..1afc953 100644
--- a/Modspec.Model/IModbusClient.cs
+++ b/Modspec.Model/IModbusClient.cs
@@ -12,10 +12,10 @@ namespace Modspec.Model;
 /// Callback invoked when a bitfield point with level annotations changes between reads.
 /// </summary>
 /// <param name="name">The name of the bitfield point that changed.</param>
-/// <param name="oldValue">The previous value of the bitfield (boxed enum).</param>
-/// <param name="newValue">The current value of the bitfield (boxed enum).</param>
+/// <param name="oldValue">The previous value of the bitfield.</param>
+/// <param name="newValue">The current value of the bitfield.</param>
 /// <param name="level">The highest severity level among the currently set flags.</param>
-public delegate void BitfieldChangedCallback(string name, object oldValue, object newValue, Level level);
+public delegate void BitfieldChangedCallback(string name, Enum oldValue, Enum newValue, Level level);
 
 /// <summary>
 /// Interface for a Modbus client.