diff --git a/src/System.ServiceModel.Primitives/ref/System.ServiceModel.Primitives.cs b/src/System.ServiceModel.Primitives/ref/System.ServiceModel.Primitives.cs
index 416b7c30658..a3ec48e5040 100644
--- a/src/System.ServiceModel.Primitives/ref/System.ServiceModel.Primitives.cs
+++ b/src/System.ServiceModel.Primitives/ref/System.ServiceModel.Primitives.cs
@@ -1574,6 +1574,10 @@ public void Add(System.ServiceModel.Channels.MessageHeaderInfo headerInfo) { }
         System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { return default; }
         public void Remove(System.ServiceModel.Channels.MessageHeaderInfo headerInfo) { }
     }
+    internal interface IMergeEnabledMessageProperty
+    {
+        bool TryMergeWithProperty(object propertyToMerge);
+    }
 }
 namespace System.ServiceModel.Description
 {