diff --git a/Triangulation_2/include/CGAL/Triangulation_2/internal/Polyline_constraint_hierarchy_2.h b/Triangulation_2/include/CGAL/Triangulation_2/internal/Polyline_constraint_hierarchy_2.h
index 037b2368a5c..0b59735b50e 100644
--- a/Triangulation_2/include/CGAL/Triangulation_2/internal/Polyline_constraint_hierarchy_2.h
+++ b/Triangulation_2/include/CGAL/Triangulation_2/internal/Polyline_constraint_hierarchy_2.h
@@ -24,6 +24,7 @@
 
 #include <CGAL/unordered_flat_map.h>
 #include <CGAL/Skiplist.h>
+#include <CGAL/Iterator_range.h>
 #include <CGAL/assertions.h>
 
 #ifdef CGAL_CDT_2_DEBUG_INTERSECTIONS