diff --git a/src/OpenFeature/Model/EvaluationContext.cs b/src/OpenFeature/Model/EvaluationContext.cs
index cea596ca..cedfba60 100644
--- a/src/OpenFeature/Model/EvaluationContext.cs
+++ b/src/OpenFeature/Model/EvaluationContext.cs
@@ -14,7 +14,8 @@ public sealed class EvaluationContext
         /// <summary>
         /// The index for the "targeting key" property when the EvaluationContext is serialized or expressed as a dictionary.
         /// </summary>
-        public readonly static string TargetingKeyIndex = "targetingKey";
+        internal const string TargetingKeyIndex = "targetingKey";
+
 
         private readonly Structure _structure;