diff --git a/test/Polly.Core.Tests/CircuitBreaker/Controller/ScheduledTaskExecutorTests.cs b/test/Polly.Core.Tests/CircuitBreaker/Controller/ScheduledTaskExecutorTests.cs
index c712ea7bb75..f24b8791324 100644
--- a/test/Polly.Core.Tests/CircuitBreaker/Controller/ScheduledTaskExecutorTests.cs
+++ b/test/Polly.Core.Tests/CircuitBreaker/Controller/ScheduledTaskExecutorTests.cs
@@ -106,7 +106,7 @@ public async Task Dispose_ScheduledTaskCancelled()
             .Throw<ObjectDisposedException>();
     }
 
-    [Fact(Skip = "TODO - Failing under .NET Framework for some reason.")]
+    [Fact]
     public void Dispose_WhenScheduledTaskExecuting()
     {
         using var disposed = new ManualResetEvent(false);
diff --git a/test/Polly.Core.Tests/Issues/IssuesTests.InfiniteRetry_2163.cs b/test/Polly.Core.Tests/Issues/IssuesTests.InfiniteRetry_2163.cs
index 68cf8484da0..518e47549fc 100644
--- a/test/Polly.Core.Tests/Issues/IssuesTests.InfiniteRetry_2163.cs
+++ b/test/Polly.Core.Tests/Issues/IssuesTests.InfiniteRetry_2163.cs
@@ -5,7 +5,7 @@ namespace Polly.Core.Tests.Issues;
 
 public partial class IssuesTests
 {
-    [Fact(Timeout = 15_000, Skip = "TODO - Failing under .NET 9 for some reason.")]
+    [Fact(Timeout = 15_000)]
     public async Task InfiniteRetry_Delay_Does_Not_Overflow_2163()
     {
         // Arrange
diff --git a/test/Polly.Core.Tests/Polly.Core.Tests.csproj b/test/Polly.Core.Tests/Polly.Core.Tests.csproj
index 574ffff8f35..9f926276c96 100644
--- a/test/Polly.Core.Tests/Polly.Core.Tests.csproj
+++ b/test/Polly.Core.Tests/Polly.Core.Tests.csproj
@@ -2,6 +2,7 @@
   <PropertyGroup>
     <TargetFrameworks>net9.0;net8.0</TargetFrameworks>
     <TargetFrameworks Condition="$([MSBuild]::IsOSPlatform('Windows'))">$(TargetFrameworks);net481</TargetFrameworks>
+    <TestTfmsInParallel Condition="$([MSBuild]::IsOSPlatform('Windows'))">false</TestTfmsInParallel>
     <ProjectType>Test</ProjectType>
     <Nullable>enable</Nullable>
     <Threshold>100</Threshold>