diff --git a/nac3core/irrt/irrt.cpp b/nac3core/irrt/irrt.cpp
index a2d97f4..722ed32 100644
--- a/nac3core/irrt/irrt.cpp
+++ b/nac3core/irrt/irrt.cpp
@@ -4,6 +4,7 @@
 #include "irrt/ndarray.hpp"
 #include "irrt/range.hpp"
 #include "irrt/slice.hpp"
+#include "irrt/string.hpp"
 #include "irrt/ndarray/basic.hpp"
 #include "irrt/ndarray/def.hpp"
 #include "irrt/ndarray/iter.hpp"