diff --git a/Intersections_3/include/CGAL/Intersections_3/internal/Iso_cuboid_3_Plane_3_intersection.h b/Intersections_3/include/CGAL/Intersections_3/internal/Iso_cuboid_3_Plane_3_intersection.h
index 270693f2fb9..94c7717bc5f 100644
--- a/Intersections_3/include/CGAL/Intersections_3/internal/Iso_cuboid_3_Plane_3_intersection.h
+++ b/Intersections_3/include/CGAL/Intersections_3/internal/Iso_cuboid_3_Plane_3_intersection.h
@@ -60,7 +60,7 @@ intersection(
     } };
 
   // description of faces of the bbox
-  constexpr std::array<int, 24> face_indices
+  static constexpr std::array<int, 24> face_indices
     { { 0, 1, 2, 3,
         2, 1, 5, 6,
         3, 2, 6, 7,
@@ -68,7 +68,7 @@ intersection(
         4, 0, 3, 7,
         6, 5, 4, 7 } };
 
-  constexpr std::array<int, 24> edge_indices
+  static constexpr std::array<int, 24> edge_indices
     { { 0,  1,  2, 3,
         1,  4,  5, 6,
         2,  6,  7, 8,
diff --git a/Intersections_3/include/CGAL/Intersections_3/internal/Tetrahedron_3_Plane_3_intersection.h b/Intersections_3/include/CGAL/Intersections_3/internal/Tetrahedron_3_Plane_3_intersection.h
index 498ab69a56e..6038a43904b 100644
--- a/Intersections_3/include/CGAL/Intersections_3/internal/Tetrahedron_3_Plane_3_intersection.h
+++ b/Intersections_3/include/CGAL/Intersections_3/internal/Tetrahedron_3_Plane_3_intersection.h
@@ -55,13 +55,13 @@ intersection(
     } };
 
   // description of faces of the bbox
-  constexpr std::array<int, 12> face_indices
+  static constexpr std::array<int, 12> face_indices
     { { 0, 1, 2,
         0, 1, 3,
         1, 2, 3,
         2, 0, 3 } };
 
-  constexpr std::array<int, 12> edge_indices
+  static constexpr std::array<int, 12> edge_indices
     { { 0,  1,  2,
         0,  3,  5,
         1,  4,  3,
diff --git a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/clip.h b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/clip.h
index e3adbbd72f1..9b278e252c3 100644
--- a/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/clip.h
+++ b/Polygon_mesh_processing/include/CGAL/Polygon_mesh_processing/clip.h
@@ -87,7 +87,7 @@ clip_to_bbox(const Plane_3& plane,
   }};
 
   // description of faces of the bbox
-  constexpr std::array<int, 24> face_indices
+  static constexpr std::array<int, 24> face_indices
     { { 0, 1, 2, 3,
         2, 1, 5, 6,
         3, 2, 6, 7,
@@ -95,7 +95,7 @@ clip_to_bbox(const Plane_3& plane,
         4, 0, 3, 7,
         6, 5, 4, 7 } };
 
-  constexpr std::array<int, 24> edge_indices
+  static constexpr std::array<int, 24> edge_indices
     { { 0,  1,  2, 3,
         1,  4,  5, 6,
         2,  6,  7, 8,