diff --git a/test/ProblemDetails.Tests/Helpers/FormattersExtensions.cs b/test/ProblemDetails.Tests/Helpers/FormattersExtensions.cs
index fa0234a..90daa91 100644
--- a/test/ProblemDetails.Tests/Helpers/FormattersExtensions.cs
+++ b/test/ProblemDetails.Tests/Helpers/FormattersExtensions.cs
@@ -1,5 +1,8 @@
-using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc;
 using Microsoft.Extensions.DependencyInjection;
+#if NET6_0_OR_GREATER
+using System.Text.Json.Serialization;
+#endif
 
 namespace ProblemDetails.Tests.Helpers
 {
@@ -12,7 +15,11 @@ public static IMvcCoreBuilder AddFormatters(this IMvcCoreBuilder mvc)
 
         private static void ConfigureJson(JsonOptions json)
         {
+#if NET6_0_OR_GREATER
+            json.JsonSerializerOptions.DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull;
+#else
             json.JsonSerializerOptions.IgnoreNullValues = true;
+#endif
         }
     }
 }