diff --git a/src/TestabilityKata.Tests/TestabilityKata.Tests.csproj b/src/TestabilityKata.Tests/TestabilityKata.Tests.csproj
index f8c14f3..14ce7f0 100644
--- a/src/TestabilityKata.Tests/TestabilityKata.Tests.csproj
+++ b/src/TestabilityKata.Tests/TestabilityKata.Tests.csproj
@@ -1,17 +1,17 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.0</TargetFramework>
+    <TargetFramework>net6.0</TargetFramework>
 
     <IsPackable>false</IsPackable>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="FluffySpoon.Testing.Autofake.Autofac" Version="1.0.5" />
-    <PackageReference Include="FluffySpoon.Testing.Autofake.NSubstitute" Version="1.0.5" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.3.0-preview-20170628-02" />
-    <PackageReference Include="MSTest.TestAdapter" Version="1.1.18" />
-    <PackageReference Include="MSTest.TestFramework" Version="1.1.18" />
+    <PackageReference Include="FluffySpoon.Testing.Autofake.Autofac" Version="1.34.0" />
+    <PackageReference Include="FluffySpoon.Testing.Autofake.NSubstitute" Version="1.34.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.2.0" />
+    <PackageReference Include="MSTest.TestAdapter" Version="2.2.10" />
+    <PackageReference Include="MSTest.TestFramework" Version="2.2.10" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/src/TestabilityKata/Program.cs b/src/TestabilityKata/Program.cs
index 64971c8..88e9322 100644
--- a/src/TestabilityKata/Program.cs
+++ b/src/TestabilityKata/Program.cs
@@ -9,7 +9,9 @@ public static void Main(string[] args)
         {
             var mailSender = new MailSender();
             new Program(
-                    new Logger(mailSender),
+                    new Logger(
+                        mailSender,
+                        new CustomFileWriterFactory(mailSender)),
                     mailSender)
                 .Run();
         }
@@ -49,15 +51,15 @@ public enum LogLevel
 
     public class Logger
     {
-        //we can't do CustomFileWriter yet, because its file name depends on the log level.
-        //see the next step for that.
-
         private readonly MailSender mailSender;
+        private readonly CustomFileWriterFactory customFileWriterFactory;
 
         public Logger(
-            MailSender mailSender)
+            MailSender mailSender,
+            CustomFileWriterFactory customFileWriterFactory)
         {
             this.mailSender = mailSender;
+            this.customFileWriterFactory = customFileWriterFactory;
         }
 
         public void Log(LogLevel logLevel, string logText)
@@ -68,7 +70,7 @@ public void Log(LogLevel logLevel, string logText)
             {
 
                 //also log to file
-                var writer = new CustomFileWriter(mailSender, @"C:\" + logLevel + "-annoying-log-file.txt");
+                var writer = customFileWriterFactory.Create(@"C:\" + logLevel + "-annoying-log-file.txt");
                 writer.AppendLine(logText);
 
                 //send e-mail about error
@@ -90,6 +92,24 @@ public void SendMail(string recipient, string content)
         }
     }
 
+    public class CustomFileWriterFactory
+    {
+        private readonly MailSender mailSender;
+
+        public CustomFileWriterFactory(
+            MailSender mailSender)
+        {
+            this.mailSender = mailSender;
+        }
+
+        public CustomFileWriter Create(string filePath)
+        {
+            return new CustomFileWriter(
+                mailSender, 
+                filePath);
+        }
+    }
+
     public class CustomFileWriter
     {
         private readonly MailSender mailSender;
diff --git a/src/TestabilityKata/TestabilityKata.csproj b/src/TestabilityKata/TestabilityKata.csproj
index ce1697a..41f1d5a 100644
--- a/src/TestabilityKata/TestabilityKata.csproj
+++ b/src/TestabilityKata/TestabilityKata.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp2.0</TargetFramework>
+    <TargetFramework>net6.0</TargetFramework>
   </PropertyGroup>
 
 </Project>