diff --git a/tests/ModelContextProtocol.Tests/ClientIntegrationTestFixture.cs b/tests/ModelContextProtocol.Tests/ClientIntegrationTestFixture.cs
index 6f0e8e44a..726a3fb1a 100644
--- a/tests/ModelContextProtocol.Tests/ClientIntegrationTestFixture.cs
+++ b/tests/ModelContextProtocol.Tests/ClientIntegrationTestFixture.cs
@@ -16,6 +16,8 @@ public class ClientIntegrationTestFixture
     public ClientIntegrationTestFixture()
     {
         const string ServerEverythingVersion = "2026.1.26";
+        string testServerExecutable = Path.Combine(AppContext.BaseDirectory, "TestServer.exe");
+        string testServerDll = Path.Combine(AppContext.BaseDirectory, "TestServer.dll");
 
         EverythingServerTransportOptions = new()
         {
@@ -27,14 +29,14 @@ public ClientIntegrationTestFixture()
 
         TestServerTransportOptions = new()
         {
-            Command = RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ? "TestServer.exe" : PlatformDetection.IsMonoRuntime ? "mono" : "dotnet",
+            Command = RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ? testServerExecutable : PlatformDetection.IsMonoRuntime ? "mono" : "dotnet",
             Name = "TestServer",
         };
 
         if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
         {
             // Change to Arguments to "mcp-server-everything" if you want to run the server locally after creating a symlink
-            TestServerTransportOptions.Arguments = [PlatformDetection.IsMonoRuntime ? "TestServer.exe" : "TestServer.dll"];
+            TestServerTransportOptions.Arguments = [PlatformDetection.IsMonoRuntime ? testServerExecutable : testServerDll];
         }
     }
 
diff --git a/tests/ModelContextProtocol.Tests/Transport/StdioClientTransportTests.cs b/tests/ModelContextProtocol.Tests/Transport/StdioClientTransportTests.cs
index 8b7876271..a709688b4 100644
--- a/tests/ModelContextProtocol.Tests/Transport/StdioClientTransportTests.cs
+++ b/tests/ModelContextProtocol.Tests/Transport/StdioClientTransportTests.cs
@@ -154,6 +154,8 @@ public async Task EscapesCliArgumentsCorrectly(string? cliArgumentValue)
         }
         
         string cliArgument = $"--cli-arg={cliArgumentValue}";
+        string testServerExecutable = Path.Combine(AppContext.BaseDirectory, "TestServer.exe");
+        string testServerDll = Path.Combine(AppContext.BaseDirectory, "TestServer.dll");
 
         StdioClientTransportOptions options = new()
         {
@@ -161,14 +163,14 @@ public async Task EscapesCliArgumentsCorrectly(string? cliArgumentValue)
             Command = (PlatformDetection.IsMonoRuntime, PlatformDetection.IsWindows) switch
             {
                 (true, _) => "mono",
-                (_, true) => "TestServer.exe",
+                (_, true) => testServerExecutable,
                 _ => "dotnet",
             },
             Arguments = (PlatformDetection.IsMonoRuntime, PlatformDetection.IsWindows) switch
             {
-                (true, _) => ["TestServer.exe", cliArgument],
+                (true, _) => [testServerExecutable, cliArgument],
                 (_, true) => [cliArgument],
-                _ => ["TestServer.dll", cliArgument],
+                _ => [testServerDll, cliArgument],
             },
         };