diff --git a/global.json b/global.json
new file mode 100644
index 0000000..3140116
--- /dev/null
+++ b/global.json
@@ -0,0 +1,5 @@
+{
+  "test": {
+    "runner": "Microsoft.Testing.Platform"
+  }
+}
diff --git a/src/DayPhaseIndicator.Tests/DayPhaseIndicator.Tests.csproj b/src/DayPhaseIndicator.Tests/DayPhaseIndicator.Tests.csproj
index 31287cc..ec0eae7 100644
--- a/src/DayPhaseIndicator.Tests/DayPhaseIndicator.Tests.csproj
+++ b/src/DayPhaseIndicator.Tests/DayPhaseIndicator.Tests.csproj
@@ -2,15 +2,15 @@
 
   <PropertyGroup>
     <TargetFramework>net10.0-windows</TargetFramework>
+    <OutputType>Exe</OutputType>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
     <IsPackable>false</IsPackable>
+    <TestingPlatformDotnetTestSupport>true</TestingPlatformDotnetTestSupport>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.4.0" />
-    <PackageReference Include="xunit" Version="2.9.3" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="3.1.5" />
+    <PackageReference Include="TUnit" Version="1.37.24" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/src/DayPhaseIndicator.Tests/PhaseLogicTests.cs b/src/DayPhaseIndicator.Tests/PhaseLogicTests.cs
index 16492c5..fa96a93 100644
--- a/src/DayPhaseIndicator.Tests/PhaseLogicTests.cs
+++ b/src/DayPhaseIndicator.Tests/PhaseLogicTests.cs
@@ -1,5 +1,4 @@
 using DayPhaseIndicator.Core;
-using Xunit;
 
 namespace DayPhaseIndicator.Tests;
 
@@ -14,60 +13,60 @@ public class PhaseLogicTests
         new(new TimeOnly(22, 0), "BOOKS / SHOWS", "#9013FE"),
     };
 
-    [Theory]
-    [InlineData(10, 0, "WORK")]
-    [InlineData(9, 0, "WORK")]        // exactly at start
-    [InlineData(16, 59, "WORK")]       // just before next phase
-    [InlineData(17, 0, "REST")]
-    [InlineData(0, 0, "SLEEP")]
-    [InlineData(3, 30, "SLEEP")]
-    [InlineData(23, 59, "BOOKS / SHOWS")]
-    public void FindCurrentPhase_StandardSchedule(int hour, int minute, string expectedLabel)
+    [Test]
+    [Arguments(10, 0, "WORK")]
+    [Arguments(9, 0, "WORK")]        // exactly at start
+    [Arguments(16, 59, "WORK")]       // just before next phase
+    [Arguments(17, 0, "REST")]
+    [Arguments(0, 0, "SLEEP")]
+    [Arguments(3, 30, "SLEEP")]
+    [Arguments(23, 59, "BOOKS / SHOWS")]
+    public async Task FindCurrentPhase_StandardSchedule(int hour, int minute, string expectedLabel)
     {
         var now = new TimeOnly(hour, minute);
         var phase = PhaseLogic.FindCurrentPhase(StandardPhases, now);
-        Assert.NotNull(phase);
-        Assert.Equal(expectedLabel, phase.Label);
+        await Assert.That(phase).IsNotNull();
+        await Assert.That(phase.Label).IsEqualTo(expectedLabel);
     }
 
-    [Fact]
-    public void FindCurrentPhase_EmptyList_ReturnsNull()
+    [Test]
+    public async Task FindCurrentPhase_EmptyList_ReturnsNull()
     {
         var result = PhaseLogic.FindCurrentPhase(new List<Phase>(), new TimeOnly(12, 0));
-        Assert.Null(result);
+        await Assert.That(result).IsNull();
     }
 
-    [Fact]
-    public void FindCurrentPhase_SinglePhase_AlwaysReturnsIt()
+    [Test]
+    public async Task FindCurrentPhase_SinglePhase_AlwaysReturnsIt()
     {
         var phases = new List<Phase> { new(new TimeOnly(9, 0), "ONLY", "#FFF") };
-        Assert.Equal("ONLY", PhaseLogic.FindCurrentPhase(phases, new TimeOnly(0, 0))!.Label);
-        Assert.Equal("ONLY", PhaseLogic.FindCurrentPhase(phases, new TimeOnly(12, 0))!.Label);
-        Assert.Equal("ONLY", PhaseLogic.FindCurrentPhase(phases, new TimeOnly(23, 59))!.Label);
+        await Assert.That(PhaseLogic.FindCurrentPhase(phases, new TimeOnly(0, 0))!.Label).IsEqualTo("ONLY");
+        await Assert.That(PhaseLogic.FindCurrentPhase(phases, new TimeOnly(12, 0))!.Label).IsEqualTo("ONLY");
+        await Assert.That(PhaseLogic.FindCurrentPhase(phases, new TimeOnly(23, 59))!.Label).IsEqualTo("ONLY");
     }
 
-    [Fact]
-    public void ComputeTimeRemaining_SameDay()
+    [Test]
+    public async Task ComputeTimeRemaining_SameDay()
     {
         var remaining = PhaseLogic.ComputeTimeRemaining(new TimeOnly(10, 0), new TimeOnly(17, 0));
-        Assert.Equal(TimeSpan.FromHours(7), remaining);
+        await Assert.That(remaining).IsEqualTo(TimeSpan.FromHours(7));
     }
 
-    [Fact]
-    public void ComputeTimeRemaining_CrossMidnight()
+    [Test]
+    public async Task ComputeTimeRemaining_CrossMidnight()
     {
         var remaining = PhaseLogic.ComputeTimeRemaining(new TimeOnly(23, 0), new TimeOnly(0, 0));
-        Assert.Equal(TimeSpan.FromHours(1), remaining);
+        await Assert.That(remaining).IsEqualTo(TimeSpan.FromHours(1));
     }
 
-    [Theory]
-    [InlineData(120, "2h 0m left")]
-    [InlineData(90, "1h 30m left")]
-    [InlineData(30, "30m left")]
-    [InlineData(0.5, "< 1m left")]
-    public void FormatRemaining_VariousValues(double minutes, string expected)
+    [Test]
+    [Arguments(120, "2h 0m left")]
+    [Arguments(90, "1h 30m left")]
+    [Arguments(30, "30m left")]
+    [Arguments(0.5, "< 1m left")]
+    public async Task FormatRemaining_VariousValues(double minutes, string expected)
     {
-        Assert.Equal(expected, PhaseLogic.FormatRemaining(TimeSpan.FromMinutes(minutes)));
+        await Assert.That(PhaseLogic.FormatRemaining(TimeSpan.FromMinutes(minutes))).IsEqualTo(expected);
     }
 }