diff --git a/src/CalculatorUnitTests/pch.h b/src/CalculatorUnitTests/pch.h
index 5e6d7b2e..aad5f6a0 100644
--- a/src/CalculatorUnitTests/pch.h
+++ b/src/CalculatorUnitTests/pch.h
@@ -40,6 +40,7 @@
 #include <locale>
 #include <sal.h>
 #include <sstream>
+#include <future>
 
 // C++\WinRT Headers
 #include "winrt/base.h"