diff --git a/src/Adapter/MSTestAdapter.PlatformServices/Deployment/TestRunDirectories.cs b/src/Adapter/MSTestAdapter.PlatformServices/Deployment/TestRunDirectories.cs
index 22c6ba3714..96c37f0eae 100644
--- a/src/Adapter/MSTestAdapter.PlatformServices/Deployment/TestRunDirectories.cs
+++ b/src/Adapter/MSTestAdapter.PlatformServices/Deployment/TestRunDirectories.cs
@@ -45,9 +45,13 @@ public TestRunDirectories(string rootDirectory, string? firstTestSource, bool is
         RootDeploymentDirectory = rootDirectory;
         InDirectory = Path.Combine(RootDeploymentDirectory, DeploymentInDirectorySuffix);
 
-        OutDirectory = isAppDomainCreationDisabled && firstTestSource is not null
-            ? Path.GetDirectoryName(firstTestSource)!
-            : Path.Combine(RootDeploymentDirectory, DeploymentOutDirectorySuffix);
+        string? testSourceDirectory = isAppDomainCreationDisabled && !StringEx.IsNullOrEmpty(firstTestSource)
+            ? Path.GetDirectoryName(firstTestSource)
+            : null;
+
+        OutDirectory = StringEx.IsNullOrEmpty(testSourceDirectory)
+            ? Path.Combine(RootDeploymentDirectory, DeploymentOutDirectorySuffix)
+            : testSourceDirectory;
 
         InMachineNameDirectory = Path.Combine(InDirectory, Environment.MachineName);
     }
diff --git a/test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Deployment/TestRunDirectoriesTests.cs b/test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Deployment/TestRunDirectoriesTests.cs
index 1fbf566525..e72d3c06f0 100644
--- a/test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Deployment/TestRunDirectoriesTests.cs
+++ b/test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Deployment/TestRunDirectoriesTests.cs
@@ -21,4 +21,19 @@ public void OutDirectoryShouldReturnCorrectDirectory()
 
     public void InMachineNameDirectoryShouldReturnMachineSpecificDeploymentDirectory()
         => _testRunDirectories.InMachineNameDirectory.Should().Be(Path.Combine(@"C:\temp\In", Environment.MachineName));
+
+    public void OutDirectoryShouldFallBackWhenFirstTestSourceIsEmpty()
+    {
+        // Simulates Android CoreCLR where Assembly.Location returns "" (before synthetic path).
+        var directories = new TestRunDirectories(@"C:\temp", firstTestSource: string.Empty, isAppDomainCreationDisabled: true);
+        directories.OutDirectory.Should().Be(@"C:\temp\Out");
+    }
+
+    public void OutDirectoryShouldFallBackWhenFirstTestSourceIsRelativePath()
+    {
+        // Simulates Android MonoVM / CoreCLR after PR #7772 where Assembly.Location
+        // is a relative filename like "MyTests.dll" with no directory component.
+        var directories = new TestRunDirectories(@"C:\temp", firstTestSource: "MyTests.dll", isAppDomainCreationDisabled: true);
+        directories.OutDirectory.Should().Be(@"C:\temp\Out");
+    }
 }