diff --git a/src/celephem/scriptobject.h b/src/celephem/scriptobject.h
index aa6d4f532..c8801dd80 100644
--- a/src/celephem/scriptobject.h
+++ b/src/celephem/scriptobject.h
@@ -17,6 +17,7 @@
 #endif
 
 #include "lua.hpp"
+#include <iostream>
 #include <string>
 #include <celengine/parser.h>