diff --git a/cake/package-tests.cake b/cake/package-tests.cake
index 2b5413ab2..7b76d14fe 100644
--- a/cake/package-tests.cake
+++ b/cake/package-tests.cake
@@ -75,7 +75,7 @@ static PackageTest Net60Test = new PackageTest(
 static PackageTest Net60X86Test = new PackageTest(
     "Net60X86Test",
     "Run mock-assembly-x86.dll under .NET 6.0",
-    "net6.0/mock-assembly-x86.dll --trace:Debug",
+    "net6.0/mock-assembly-x86.dll",
     MockAssemblyExpectedResult(1));
 
 static PackageTest Net50Test = new PackageTest(
diff --git a/src/NUnitEngine/nunit.engine.tests/Services/RuntimeFrameworkServiceTests.cs b/src/NUnitEngine/nunit.engine.tests/Services/RuntimeFrameworkServiceTests.cs
index d61517e06..744cd0617 100644
--- a/src/NUnitEngine/nunit.engine.tests/Services/RuntimeFrameworkServiceTests.cs
+++ b/src/NUnitEngine/nunit.engine.tests/Services/RuntimeFrameworkServiceTests.cs
@@ -35,6 +35,7 @@ public void ServiceIsStarted()
         [TestCase("mock-assembly.dll", false)]
         [TestCase("../agents/net20/nunit-agent.exe", false)]
         [TestCase("../agents/net20/nunit-agent-x86.exe", true)]
+        [TestCase("../netstandard2.0/nunit.engine.api.dll", false)]
         public void SelectRuntimeFramework(string assemblyName, bool runAsX86)
         {
             var package = new TestPackage(Path.Combine(TestContext.CurrentContext.TestDirectory, assemblyName));
diff --git a/src/NUnitEngine/nunit.engine/Services/RuntimeFrameworkService.cs b/src/NUnitEngine/nunit.engine/Services/RuntimeFrameworkService.cs
index 673b76420..e1f7538d1 100644
--- a/src/NUnitEngine/nunit.engine/Services/RuntimeFrameworkService.cs
+++ b/src/NUnitEngine/nunit.engine/Services/RuntimeFrameworkService.cs
@@ -140,7 +140,7 @@ private RuntimeFramework SelectRuntimeFrameworkInner(TestPackage package)
 
             if (string.IsNullOrEmpty(imageTargetFrameworkNameSetting))
             {
-                // Assume .NET Framework
+                // Assume .NET Framework 2.0
                 targetRuntime = currentFramework.Runtime;
                 targetVersion = package.GetSetting(InternalEnginePackageSettings.ImageRuntimeVersion, new Version(2, 0));
             }
@@ -152,15 +152,19 @@ private RuntimeFramework SelectRuntimeFrameworkInner(TestPackage package)
                 {
                     case ".NETFramework":
                         targetRuntime = RuntimeType.Net;
+                        targetVersion = frameworkName.Version;
                         break;
                     case ".NETCoreApp":
                         targetRuntime = RuntimeType.NetCore;
+                        targetVersion = frameworkName.Version;
+                        break;
+                    case ".NETStandard":
+                        targetRuntime = RuntimeType.NetCore;
+                        targetVersion = new Version(3, 1);
                         break;
                     default:
                         throw new NUnitEngineException("Unsupported Target Framework: " + imageTargetFrameworkNameSetting);
                 }
-
-                targetVersion = frameworkName.Version;
             }
 
             if (!IsAvailable(new RuntimeFramework(targetRuntime, targetVersion).Id, runAsX86))