diff --git a/onnxruntime/core/mlas/lib/mlasi.h b/onnxruntime/core/mlas/lib/mlasi.h
index 47a802851b50f..bd8a0effcf741 100644
--- a/onnxruntime/core/mlas/lib/mlasi.h
+++ b/onnxruntime/core/mlas/lib/mlasi.h
@@ -517,7 +517,7 @@ MlasGetMaximumThreadCount(
     MLAS_UNREFERENCED_PARAMETER(ThreadPool);
 #else
     if (ThreadPool != nullptr) {
-        return ThreadPool->NumThreads();
+        return ThreadPool->NumThreads() + 1;
     }
 #endif