diff --git a/tests/rgen/Microsoft.Macios.Transformer.Tests/BaseTransformerTestClass.cs b/tests/rgen/Microsoft.Macios.Transformer.Tests/BaseTransformerTestClass.cs
index e8dd76808408..329c21995b07 100644
--- a/tests/rgen/Microsoft.Macios.Transformer.Tests/BaseTransformerTestClass.cs
+++ b/tests/rgen/Microsoft.Macios.Transformer.Tests/BaseTransformerTestClass.cs
@@ -1,7 +1,6 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
-using System.Collections.Immutable;
 using System.Runtime.CompilerServices;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
diff --git a/tests/rgen/Microsoft.Macios.Transformer.Tests/Microsoft.Macios.Transformer.Tests.csproj b/tests/rgen/Microsoft.Macios.Transformer.Tests/Microsoft.Macios.Transformer.Tests.csproj
index 7ee72ccb9417..dca7ca187863 100644
--- a/tests/rgen/Microsoft.Macios.Transformer.Tests/Microsoft.Macios.Transformer.Tests.csproj
+++ b/tests/rgen/Microsoft.Macios.Transformer.Tests/Microsoft.Macios.Transformer.Tests.csproj
@@ -1,50 +1,62 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
-  <PropertyGroup>
-    <TargetFramework>net$(BundledNETCoreAppTargetFrameworkVersion)</TargetFramework>
-    <ImplicitUsings>enable</ImplicitUsings>
-    <Nullable>enable</Nullable>
-    <IsPackable>false</IsPackable>
-  </PropertyGroup>
+    <PropertyGroup>
+        <TargetFramework>net$(BundledNETCoreAppTargetFrameworkVersion)</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+        <IsPackable>false</IsPackable>
 
-  <ItemGroup>
-    <PackageReference Include="coverlet.collector" Version="6.0.2" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.10.0" />
-    <PackageReference Include="xunit" Version="2.9.0" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2" />
-  </ItemGroup>
+        <!-- Ensure we do have the api-definitions -->
+        <RootDirectory>$([System.IO.Path]::GetFullPath('$(MSBuildThisFileDirectory)\..\..\..'))</RootDirectory>
+        <DotnetBuildDirectory>$(RootDirectory)/src/build/dotnet</DotnetBuildDirectory>
+    </PropertyGroup>
 
-  <ItemGroup>
-    <Using Include="Xunit" />
-  </ItemGroup>
+    <ItemGroup>
+        <PackageReference Include="coverlet.collector" Version="6.0.2"/>
+        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.10.0"/>
+        <PackageReference Include="xunit" Version="2.9.0"/>
+        <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2"/>
+    </ItemGroup>
 
-  <ItemGroup>
-      <ProjectReference Include="..\..\..\src\rgen\Microsoft.Macios.Transformer\Microsoft.Macios.Transformer.csproj" />
-      <ProjectReference Include="..\..\..\src\rgen\Microsoft.Macios.Binding.Common\Microsoft.Macios.Binding.Common.csproj" />
-  </ItemGroup>
+    <ItemGroup>
+        <Using Include="Xunit"/>
+    </ItemGroup>
 
-  <ItemGroup>
-      <Compile Include="..\..\common\Configuration.cs" >
-          <Link>external\Configuration.cs</Link>
-      </Compile>
-      <Compile Include="..\..\common\ConfigurationXUnit.cs" >
-          <Link>external\ConfigurationXUnit.cs</Link>
-      </Compile>
-      <Compile Include="..\..\common\Profile.cs">
-          <Link>external\Profile.cs</Link>
-      </Compile>
-      <Compile Include="..\..\common\ExecutionHelper.cs">
-          <Link>external\ExecutionHelper.cs</Link>
-      </Compile>
-      <Compile Include="..\..\..\tools\common\StringUtils.cs">
-          <Link>external\StringUtils.cs</Link>
-      </Compile>
-      <Compile Include="..\..\..\tools\common\Execution.cs">
-          <Link>external\Execution.cs</Link>
-      </Compile>
-      <Compile Include="..\..\mtouch\Cache.cs">
-          <Link>external\Cache.cs</Link>
-      </Compile>
-  </ItemGroup>
+    <ItemGroup>
+        <ProjectReference Include="..\..\..\src\rgen\Microsoft.Macios.Transformer\Microsoft.Macios.Transformer.csproj"/>
+        <ProjectReference Include="..\..\..\src\rgen\Microsoft.Macios.Binding.Common\Microsoft.Macios.Binding.Common.csproj"/>
+    </ItemGroup>
+
+    <ItemGroup>
+        <Compile Include="..\..\common\Configuration.cs">
+            <Link>external\Configuration.cs</Link>
+        </Compile>
+        <Compile Include="..\..\common\ConfigurationXUnit.cs">
+            <Link>external\ConfigurationXUnit.cs</Link>
+        </Compile>
+        <Compile Include="..\..\common\Profile.cs">
+            <Link>external\Profile.cs</Link>
+        </Compile>
+        <Compile Include="..\..\common\ExecutionHelper.cs">
+            <Link>external\ExecutionHelper.cs</Link>
+        </Compile>
+        <Compile Include="..\..\..\tools\common\StringUtils.cs">
+            <Link>external\StringUtils.cs</Link>
+        </Compile>
+        <Compile Include="..\..\..\tools\common\Execution.cs">
+            <Link>external\Execution.cs</Link>
+        </Compile>
+        <Compile Include="..\..\mtouch\Cache.cs">
+            <Link>external\Cache.cs</Link>
+        </Compile>
+    </ItemGroup>
+    
+    <Target Name="BuildTestLibraries" BeforeTargets="BeforeBuild">
+        <Message Text="Processing platform: %(Platform.Identity)" /> 
+        <Exec Command="make -j8 -C $(RootDirectory) $(DotnetBuildDirectory)/ios/apidefinition-ios.dll"/>
+        <Exec Command="make -j8 -C $(RootDirectory) $(DotnetBuildDirectory)/macos/apidefinition-macos.dll"/>
+        <Exec Command="make -j8 -C $(RootDirectory) $(DotnetBuildDirectory)/tvos/apidefinition-tvos.dll"/>
+        <Exec Command="make -j8 -C $(RootDirectory) $(DotnetBuildDirectory)/maccatalyst/apidefinition-maccatalyst.dll"/>
+    </Target>
 
 </Project>