diff --git a/exercises/testing-code/solution/Workflow/TemporalDurableExecution.Workflow.csproj b/exercises/testing-code/solution/Workflow/TemporalDurableExecution.Workflow.csproj
index a5b9e0e..8ddd661 100644
--- a/exercises/testing-code/solution/Workflow/TemporalDurableExecution.Workflow.csproj
+++ b/exercises/testing-code/solution/Workflow/TemporalDurableExecution.Workflow.csproj
@@ -1,2 +1,5 @@
 <Project Sdk="Microsoft.NET.Sdk">
+  <ItemGroup>
+    <PackageReference Include="System.Text.Json" Version="8.0.5" />
+  </ItemGroup>
 </Project>
\ No newline at end of file