diff --git a/exercises/testing-code/solution/Tests/ActivityTest.cs b/exercises/testing-code/solution/Tests/ActivityTest.cs
index 3f966cc..2f8ca4d 100644
--- a/exercises/testing-code/solution/Tests/ActivityTest.cs
+++ b/exercises/testing-code/solution/Tests/ActivityTest.cs
@@ -4,7 +4,7 @@ namespace TemporalDurableExecution.Tests;
 using TemporalioDurableExecution.Workflow;
 using Xunit;
 
-public class TranslationActivityTests
+internal class TranslationActivityTests
 {
     private static readonly HttpClient Client = new HttpClient();
 
diff --git a/exercises/testing-code/solution/Tests/TranslationWorkflowMockTests.cs b/exercises/testing-code/solution/Tests/TranslationWorkflowMockTests.cs
index e76c941..51bad43 100644
--- a/exercises/testing-code/solution/Tests/TranslationWorkflowMockTests.cs
+++ b/exercises/testing-code/solution/Tests/TranslationWorkflowMockTests.cs
@@ -6,7 +6,7 @@ namespace TemporalDurableExecution.Tests;
 using TemporalioDurableExecution.Workflow;
 using Xunit;
 
-public class TranslationWorkflowMockTests
+internal class TranslationWorkflowMockTests
 {
     private static readonly HttpClient Client = new HttpClient();
 
diff --git a/exercises/testing-code/solution/Tests/TranslationWorkflowTests.cs b/exercises/testing-code/solution/Tests/TranslationWorkflowTests.cs
index 0b01bc0..c58fc00 100644
--- a/exercises/testing-code/solution/Tests/TranslationWorkflowTests.cs
+++ b/exercises/testing-code/solution/Tests/TranslationWorkflowTests.cs
@@ -6,7 +6,7 @@ namespace TemporalDurableExecution.Workflow;
 using TemporalioDurableExecution.Workflow;
 using Xunit;
 
-public class TranslationWorkflowTests
+internal class TranslationWorkflowTests
 {
     private static readonly HttpClient Client = new HttpClient();