diff --git a/packages/vaex-core/src/superstring.hpp b/packages/vaex-core/src/superstring.hpp
index b62d492bc2..924be203bc 100644
--- a/packages/vaex-core/src/superstring.hpp
+++ b/packages/vaex-core/src/superstring.hpp
@@ -3,6 +3,7 @@
 
 #include <nonstd/string_view.hpp>
 #include <string>
+#include <iostream>
 typedef nonstd::string_view string_view;
 typedef std::string string;
 #include <pybind11/numpy.h>