diff --git a/src/Umbraco.Core/Models/ContentEditing/ContentItemDisplay.cs b/src/Umbraco.Core/Models/ContentEditing/ContentItemDisplay.cs
index eb800791a2..d1a8d10970 100644
--- a/src/Umbraco.Core/Models/ContentEditing/ContentItemDisplay.cs
+++ b/src/Umbraco.Core/Models/ContentEditing/ContentItemDisplay.cs
@@ -201,7 +201,7 @@ public class ContentItemDisplay<TVariant> :
     /// </summary>
     [DataMember(Name = "metaData")]
     [ReadOnly(true)]
-    public IDictionary<string, object>? AdditionalData { get; private set; }
+    public IDictionary<string, object> AdditionalData { get; private set; } = new Dictionary<string, object>();
 
     /// <summary>
     ///     This is used for validation of a content item.