diff --git a/src/OpenFeature/Model/EvaluationContextBuilder.cs b/src/OpenFeature/Model/EvaluationContextBuilder.cs
index d86ad44b..89174cf6 100644
--- a/src/OpenFeature/Model/EvaluationContextBuilder.cs
+++ b/src/OpenFeature/Model/EvaluationContextBuilder.cs
@@ -140,17 +140,17 @@ public EvaluationContextBuilder Merge(EvaluationContext context)
         {
             string newTargetingKey = "";
 
-            if (!string.IsNullOrWhitespace(TargetingKey))
+            if (!string.IsNullOrWhiteSpace(TargetingKey))
             {
                 newTargetingKey = TargetingKey;
             }
 
-            if (!string.IsNullOrWhitespace(context.TargetingKey))
+            if (!string.IsNullOrWhiteSpace(context.TargetingKey))
             {
                 newTargetingKey = context.TargetingKey;
             }
 
-            if (!string.IsNullOrWhitespace(newTargetingKey))
+            if (!string.IsNullOrWhiteSpace(newTargetingKey))
             {
                 this.TargetingKey = newTargetingKey;
             }