diff --git a/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/Octree_wrapper.h b/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/Octree_wrapper.h
index 6228b68c842..6cdfd510843 100644
--- a/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/Octree_wrapper.h
+++ b/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/Octree_wrapper.h
@@ -21,6 +21,8 @@
 #include <CGAL/Octree.h>
 #include <CGAL/Orthtree/Traversals.h>
 
+#include <boost/functional/hash.hpp>
+
 #include <array>
 #include <map>
 #include <tuple>
diff --git a/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/partition_traits_Cartesian_grid.h b/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/partition_traits_Cartesian_grid.h
index 94d18dfbcfd..322a75d5a56 100644
--- a/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/partition_traits_Cartesian_grid.h
+++ b/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/partition_traits_Cartesian_grid.h
@@ -26,6 +26,8 @@
 #include <tbb/blocked_range3d.h>
 #endif // CGAL_LINKED_WITH_TBB
 
+#include <boost/functional/hash.hpp>
+
 #include <array>
 
 namespace CGAL {
diff --git a/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/partition_traits_Octree.h b/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/partition_traits_Octree.h
index d474214c833..0916ba1b590 100644
--- a/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/partition_traits_Octree.h
+++ b/Isosurfacing_3/include/CGAL/Isosurfacing_3/internal/partition_traits_Octree.h
@@ -18,6 +18,8 @@
 #include <CGAL/Isosurfacing_3/internal/Octree_wrapper.h>
 #include <CGAL/Isosurfacing_3/internal/Cell_type.h>
 
+#include <CGAL/tags.h>
+
 #ifdef CGAL_LINKED_WITH_TBB
 #include <tbb/parallel_for.h>
 #endif // CGAL_LINKED_WITH_TBB