diff --git a/Constrained_triangulation_3/include/CGAL/Conforming_constrained_Delaunay_triangulation_3.h b/Constrained_triangulation_3/include/CGAL/Conforming_constrained_Delaunay_triangulation_3.h
index d98ab0e839d..1a070a77585 100644
--- a/Constrained_triangulation_3/include/CGAL/Conforming_constrained_Delaunay_triangulation_3.h
+++ b/Constrained_triangulation_3/include/CGAL/Conforming_constrained_Delaunay_triangulation_3.h
@@ -563,8 +563,13 @@ private:
 
 public:
   using Vertex_handle = typename Triangulation::Vertex_handle;
+
+#ifdef DOXYGEN_RUNNING
+  using Constrained_polyline_id = unspecified_type;
+#else
   using Constrained_polyline_id = typename CDT_3_impl::Constrained_polyline_id;
-  using size_type = typename CDT_3_impl::size_type;
+#endif // not DOXYGEN_RUNNING
+  using size_type = typename Triangulation::size_type;
 
 public:
   /** \name Constructors
diff --git a/Constrained_triangulation_3/include/CGAL/Conforming_constrained_Delaunay_triangulation_cell_data_3.h b/Constrained_triangulation_3/include/CGAL/Conforming_constrained_Delaunay_triangulation_cell_data_3.h
index f596087b164..f687b715ff1 100644
--- a/Constrained_triangulation_3/include/CGAL/Conforming_constrained_Delaunay_triangulation_cell_data_3.h
+++ b/Constrained_triangulation_3/include/CGAL/Conforming_constrained_Delaunay_triangulation_cell_data_3.h
@@ -67,6 +67,8 @@ class Conforming_constrained_Delaunay_triangulation_cell_data_3 {
     return cdt.tds().faces().iterator_to(*ptr);
   }
 public:
+  /// @{
+  // @cond SKIP_IN_MANUAL
   bool is_facet_constrained(int i) const { return face_id[unsigned(i)] >= 0; }
 
   CDT_3_signed_index face_constraint_index(int i) const {
@@ -76,6 +78,7 @@ public:
   void set_face_constraint_index(int i, CDT_3_signed_index index) {
     face_id[unsigned(i)] = index;
   }
+  /// @endcond
 };
 
 } // namespace CGAL