diff --git a/onnxruntime/test/perftest/ort_test_session.cc b/onnxruntime/test/perftest/ort_test_session.cc
index d1e526b60b..1fa9a9133c 100644
--- a/onnxruntime/test/perftest/ort_test_session.cc
+++ b/onnxruntime/test/perftest/ort_test_session.cc
@@ -79,7 +79,9 @@ OnnxRuntimeTestSession::OnnxRuntimeTestSession(Ort::Env& env, std::random_device
   else
     session_options.DisableSequentialExecution();
   fprintf(stdout, "Setting thread pool size to %d\n", performance_test_config.run_config.session_thread_pool_size);
-  session_options.SetThreadPoolSize(performance_test_config.run_config.session_thread_pool_size);
+  // Don't set the thread pool size unless it has been changed from our zero default value (as zero will fail)
+  if (performance_test_config.run_config.session_thread_pool_size != 0)
+    session_options.SetThreadPoolSize(performance_test_config.run_config.session_thread_pool_size);
   // Set optimization level.
   session_options.SetGraphOptimizationLevel(performance_test_config.run_config.optimization_level);
   if (!performance_test_config.run_config.profile_file.empty())