diff --git a/src/AmbientTasks.Tests/AmbientTasks.Tests.csproj b/src/AmbientTasks.Tests/AmbientTasks.Tests.csproj
index 8d16542..dfa58fa 100644
--- a/src/AmbientTasks.Tests/AmbientTasks.Tests.csproj
+++ b/src/AmbientTasks.Tests/AmbientTasks.Tests.csproj
@@ -1,16 +1,16 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netcoreapp2.1;netcoreapp3.1;net5.0;net472</TargetFrameworks>
+    <TargetFrameworks>net6.0;net472</TargetFrameworks>
     <RootNamespace>Techsola</RootNamespace>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="AltCover" Version="7.3.806" />
-    <PackageReference Include="nunit" Version="3.12.0" />
-    <PackageReference Include="NUnit3TestAdapter" Version="3.16.1" PrivateAssets="all" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.4.0" />
-    <PackageReference Include="Shouldly" Version="3.0.2" />
+    <PackageReference Include="AltCover" Version="8.6.68" />
+    <PackageReference Include="nunit" Version="3.13.3" />
+    <PackageReference Include="NUnit3TestAdapter" Version="4.5.0" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.7.2" />
+    <PackageReference Include="Shouldly" Version="4.2.1" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/src/AmbientTasks.Tests/AmbientTasksPostTests.cs b/src/AmbientTasks.Tests/AmbientTasksPostTests.cs
index 0faefed..b2678d1 100644
--- a/src/AmbientTasks.Tests/AmbientTasksPostTests.cs
+++ b/src/AmbientTasks.Tests/AmbientTasksPostTests.cs
@@ -413,7 +413,7 @@ public static void Subsequent_invocations_by_SynchronizationContext_are_ignored_
             }
 
             callCount.ShouldBe(0);
-            Should.Throw<Exception>(postedAction);
+            Should.Throw<Exception>(postedAction!);
             callCount.ShouldBe(1);
 
             postedAction.ShouldNotBeNull();
diff --git a/src/AmbientTasks.Tests/RequireOnAllTestMethodsAttribute.cs b/src/AmbientTasks.Tests/RequireOnAllTestMethodsAttribute.cs
index 46dbc26..8266334 100644
--- a/src/AmbientTasks.Tests/RequireOnAllTestMethodsAttribute.cs
+++ b/src/AmbientTasks.Tests/RequireOnAllTestMethodsAttribute.cs
@@ -21,7 +21,7 @@ public void BeforeTest(ITest test)
         {
             var missingTypes = attributeTypes
                 .Except(
-                    from data in test.Method.MethodInfo.GetCustomAttributesData()
+                    from data in test.Method!.MethodInfo.GetCustomAttributesData()
                     select data.AttributeType)
                 .ToList();
 
diff --git a/src/AmbientTasks/AmbientTasks.csproj b/src/AmbientTasks/AmbientTasks.csproj
index 5b45f60..9ae4a63 100644
--- a/src/AmbientTasks/AmbientTasks.csproj
+++ b/src/AmbientTasks/AmbientTasks.csproj
@@ -26,7 +26,6 @@
 
   <ItemGroup>
     <PackageReference Include="DotNetAnalyzers.DocumentationAnalyzers" Version="1.0.0-beta.59" PrivateAssets="all" />
-    <PackageReference Include="Microsoft.CodeAnalysis.FxCopAnalyzers" Version="2.9.8" PrivateAssets="all" />
     <PackageReference Include="Microsoft.DotNet.Analyzers.Compatibility" Version="0.2.12-alpha" PrivateAssets="all" />
   </ItemGroup>
 
diff --git a/src/Directory.Build.props b/src/Directory.Build.props
index 05d1bc8..a2c8810 100644
--- a/src/Directory.Build.props
+++ b/src/Directory.Build.props
@@ -9,7 +9,7 @@
 
   <ItemGroup>
     <PackageReference Include="TunnelVisionLabs.ReferenceAssemblyAnnotator" Version="1.0.0-alpha.160" PrivateAssets="all" />
-    <PackageDownload Include="Microsoft.NETCore.App.Ref" Version="[5.0.0]" />
+    <PackageDownload Include="Microsoft.NETCore.App.Ref" Version="[6.0.0]" />
   </ItemGroup>
 
 </Project>