diff --git a/ubi/watch.hpp b/ubi/watch.hpp
index 4d195a3..2e0ec17 100644
--- a/ubi/watch.hpp
+++ b/ubi/watch.hpp
@@ -5,6 +5,7 @@
 
 #include <functional>
 #include <memory>
+#include <string>
 
 namespace openpower
 {