diff --git a/eng/pipelines/common/evaluate-default-paths.yml b/eng/pipelines/common/evaluate-default-paths.yml
index be1e09f93e2071..72a85c66f02efd 100644
--- a/eng/pipelines/common/evaluate-default-paths.yml
+++ b/eng/pipelines/common/evaluate-default-paths.yml
@@ -12,6 +12,7 @@ parameters:
         src/libraries/sendtohelix-wasm.targets
         src/mono/nuget/Microsoft.NET.Runtime.WebAssembly.Sdk/*
         src/mono/nuget/Microsoft.NET.Runtime.wasm.Sample.Mono/*
+        src/mono/sample/wasm/*
         src/mono/wasi/*
         src/mono/wasm/*
         src/tasks/WasmAppBuilder/*
diff --git a/src/mono/sample/wasm/Directory.Build.targets b/src/mono/sample/wasm/Directory.Build.targets
index c01bfada90c654..8970dc1dc37161 100644
--- a/src/mono/sample/wasm/Directory.Build.targets
+++ b/src/mono/sample/wasm/Directory.Build.targets
@@ -7,6 +7,7 @@
     <RunScriptInputName Condition="'$(TargetOS)' == 'Browser' and '$(OS)' == 'Windows_NT'">WasmRunnerTemplate.cmd</RunScriptInputName>
 
     <RunScriptOutputPath>$([MSBuild]::NormalizePath('$(WasmAppDir)', '$(RunScriptOutputName)'))</RunScriptOutputPath>
+    <WasmXHarnessArgs Condition="'$(WasmEnableThreads)' == 'true' or '$(WasmEnablePerfTracing)' == 'true' or '$(MonoWasmBuildVariant)' == 'perftrace' or '$(MonoWasmBuildVariant)' == 'multithread'">$(WasmXHarnessArgs) --web-server-use-cop</WasmXHarnessArgs>
   </PropertyGroup>
 
   <Target Name="BuildSampleInTree"