diff --git a/contrib/epee/include/string_tools.h b/contrib/epee/include/string_tools.h
index 8cf56e5a..ad6e253d 100644
--- a/contrib/epee/include/string_tools.h
+++ b/contrib/epee/include/string_tools.h
@@ -28,6 +28,7 @@
 
 #include <locale>
 #include <cstdlib>
+#include <iomanip>
 #include <map>
 #include <boost/uuid/uuid.hpp>
 #include <boost/uuid/uuid_io.hpp>