diff --git a/Arrangement_on_surface_2/include/CGAL/Arr_linear_traits_2.h b/Arrangement_on_surface_2/include/CGAL/Arr_linear_traits_2.h
index 300d46dc67a..36ca18b980b 100644
--- a/Arrangement_on_surface_2/include/CGAL/Arr_linear_traits_2.h
+++ b/Arrangement_on_surface_2/include/CGAL/Arr_linear_traits_2.h
@@ -28,6 +28,7 @@
 
 #include <variant>
 
+#include <CGAL/Cartesian.h>
 #include <CGAL/tags.h>
 #include <CGAL/intersections.h>
 #include <CGAL/Arr_tags.h>