diff --git a/Chapter-1-initial-architecture/Src/Fitnet.UnitTests/GlobalExceptionHandlerTests.cs b/Chapter-1-initial-architecture/Src/Fitnet.UnitTests/GlobalExceptionHandlerTests.cs
index f76823c1..11372fcf 100644
--- a/Chapter-1-initial-architecture/Src/Fitnet.UnitTests/GlobalExceptionHandlerTests.cs
+++ b/Chapter-1-initial-architecture/Src/Fitnet.UnitTests/GlobalExceptionHandlerTests.cs
@@ -5,6 +5,7 @@ namespace EvolutionaryArchitecture.Fitnet.UnitTests;
 using System.Net;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.Extensions.Logging;
+using Newtonsoft.Json;
 
 public sealed class GlobalExceptionHandlerTests
 {
@@ -61,8 +62,7 @@ private async Task<ProblemDetails> GetExceptionResponseMessage()
         _context.Response.Body.Seek(0, SeekOrigin.Begin);
         using var streamReader = new StreamReader(_context.Response.Body);
         var responseBody = await streamReader.ReadToEndAsync();
-        var problemDetails = JsonSerializer.Deserialize<ProblemDetails>(responseBody);
-
+        var problemDetails = JsonConvert.DeserializeObject<ProblemDetails>(responseBody);
         return problemDetails!;
     }
 }
diff --git a/Chapter-1-initial-architecture/Src/Fitnet.UnitTests/GlobalUsings.cs b/Chapter-1-initial-architecture/Src/Fitnet.UnitTests/GlobalUsings.cs
index 2b655069..d4802e93 100644
--- a/Chapter-1-initial-architecture/Src/Fitnet.UnitTests/GlobalUsings.cs
+++ b/Chapter-1-initial-architecture/Src/Fitnet.UnitTests/GlobalUsings.cs
@@ -1,9 +1,8 @@
 // Global using directives
 
 global using System.Collections;
-global using System.Text.Json;
 global using Bogus;
 global using FluentAssertions;
 global using Microsoft.AspNetCore.Http;
 global using NSubstitute;
-global using Xunit;
\ No newline at end of file
+global using Xunit;