1 files changed, 3 insertions, 0 deletions
diff --git a/LibMatrix.EventTypes/EventContent.cs b/LibMatrix.EventTypes/EventContent.cs
index a837252..89686ae 100644
--- a/LibMatrix.EventTypes/EventContent.cs
+++ b/LibMatrix.EventTypes/EventContent.cs
@@ -6,6 +6,9 @@ using System.Text.Json.Serialization;
 namespace LibMatrix.EventTypes;
 
 public abstract class EventContent {
+    [JsonExtensionData]
+    public Dictionary<string, JsonElement>? AdditionalData { get; set; } = [];
+
     public static List<string> GetMatchingEventTypes<T>() where T : EventContent {
         var type = typeof(T);
         var eventTypes = new List<string>();