diff --git a/base/inc/TestIO.h b/base/inc/TestIO.h
index 7d28c32..08a9167 100644
--- a/base/inc/TestIO.h
+++ b/base/inc/TestIO.h
@@ -17,6 +17,7 @@
 #define Force_TestIO_H

 #include <map>
+#include <string>

 #include "Defines.h"