diff --git a/open_engine/include/open_engine/instrumentor.hpp b/open_engine/include/open_engine/instrumentor.hpp
index 41ffb73..798a8cf 100644
--- a/open_engine/include/open_engine/instrumentor.hpp
+++ b/open_engine/include/open_engine/instrumentor.hpp
@@ -3,6 +3,7 @@
 
 #include "open_engine/logging.hpp"
 
+#include <iomanip>
 #include <mutex>
 #include <sstream>
 #include <string>