diff --git a/lib/csharp/microsoft.bot.builder.skills/Microsoft.Bot.Builder.Skills.Tests/Mocks/MockBot.cs b/lib/csharp/microsoft.bot.builder.skills/Microsoft.Bot.Builder.Skills.Tests/Mocks/MockBot.cs
index adef4300ff..67f3875941 100644
--- a/lib/csharp/microsoft.bot.builder.skills/Microsoft.Bot.Builder.Skills.Tests/Mocks/MockBot.cs
+++ b/lib/csharp/microsoft.bot.builder.skills/Microsoft.Bot.Builder.Skills.Tests/Mocks/MockBot.cs
@@ -5,7 +5,7 @@ namespace Microsoft.Bot.Builder.Skills.Tests.Mocks
 {
     public class MockBot : IBot
     {
-        public Task OnTurnAsync(ITurnContext turnContext, CancellationToken cancellationToken = default)
+        public Task OnTurnAsync(ITurnContext turnContext, CancellationToken cancellationToken = default(CancellationToken))
         {
             return Task.CompletedTask;
         }
diff --git a/lib/csharp/microsoft.bot.builder.skills/Microsoft.Bot.Builder.Skills.Tests/Mocks/MockBotFrameworkHttpAdapter.cs b/lib/csharp/microsoft.bot.builder.skills/Microsoft.Bot.Builder.Skills.Tests/Mocks/MockBotFrameworkHttpAdapter.cs
index 06c7e8db7f..393377927a 100644
--- a/lib/csharp/microsoft.bot.builder.skills/Microsoft.Bot.Builder.Skills.Tests/Mocks/MockBotFrameworkHttpAdapter.cs
+++ b/lib/csharp/microsoft.bot.builder.skills/Microsoft.Bot.Builder.Skills.Tests/Mocks/MockBotFrameworkHttpAdapter.cs
@@ -7,7 +7,7 @@ namespace Microsoft.Bot.Builder.Skills.Tests.Mocks
 {
     public class MockBotFrameworkHttpAdapter : IBotFrameworkHttpAdapter
     {
-        public Task ProcessAsync(HttpRequest httpRequest, HttpResponse httpResponse, IBot bot, CancellationToken cancellationToken = default)
+        public Task ProcessAsync(HttpRequest httpRequest, HttpResponse httpResponse, IBot bot, CancellationToken cancellationToken = default(CancellationToken))
         {
             return Task.CompletedTask;
         }