diff --git a/Frechet_distance/include/CGAL/Frechet_distance/internal/Frechet_distance.h b/Frechet_distance/include/CGAL/Frechet_distance/internal/Frechet_distance.h
index c2a1a29f8f3f..cf07d417b604 100644
--- a/Frechet_distance/include/CGAL/Frechet_distance/internal/Frechet_distance.h
+++ b/Frechet_distance/include/CGAL/Frechet_distance/internal/Frechet_distance.h
@@ -19,11 +19,11 @@
 #include <CGAL/Frechet_distance/internal/curve.h>
 #include <CGAL/Frechet_distance/internal/frechet_light.h>
 #include <CGAL/Frechet_distance/internal/geometry_basics.h>
+#include <CGAL/Frechet_distance/internal/Frechet_distance_traits.h>
 #include <CGAL/STL_Extension/internal/Has_nested_type_Has_filtered_predicates_tag.h>
 #include <CGAL/Frechet_distance_traits_2.h>
 #include <CGAL/Frechet_distance_traits_3.h>
 #include <CGAL/Frechet_distance_traits_d.h>
-#include <CGAL/Frechet_distance_traits.h>
 #include <CGAL/Simple_cartesian.h>
 #include <CGAL/Exact_rational.h>
 #include <CGAL/Interval_nt.h>
@@ -74,8 +74,8 @@ auto toCurve(const PointRange& point_range, const Traits& traits)
       }
       else
       {
-        using AT = Frechet_distance_traits<CGAL::Interval_nt_advanced, Traits::Dimension::value>;
-        using ET = Frechet_distance_traits<CGAL::Exact_rational, Traits::Dimension::value>;
+        using AT = Frechet_distance_::internal::Frechet_distance_traits<CGAL::Interval_nt_advanced, Traits::Dimension::value>;
+        using ET = Frechet_distance_::internal::Frechet_distance_traits<CGAL::Exact_rational, Traits::Dimension::value>;
         using Filtered_traits = std::pair<AT,ET>;
 
         return Curve<Filtered_traits, true>(point_range, traits);
diff --git a/Frechet_distance/include/CGAL/Frechet_distance_traits.h b/Frechet_distance/include/CGAL/Frechet_distance/internal/Frechet_distance_traits.h
similarity index 92%
rename from Frechet_distance/include/CGAL/Frechet_distance_traits.h
rename to Frechet_distance/include/CGAL/Frechet_distance/internal/Frechet_distance_traits.h
index 92abd6faf930..ef48533bb957 100644
--- a/Frechet_distance/include/CGAL/Frechet_distance_traits.h
+++ b/Frechet_distance/include/CGAL/Frechet_distance/internal/Frechet_distance_traits.h
@@ -13,16 +13,16 @@
 //                 Andreas Fabri
 // =============================================================================
 
-#ifndef CGAL_FRECHET_DISTANCE_TRAITS_H
-#define CGAL_FRECHET_DISTANCE_TRAITS_H
+#pragma once
 
 #include <CGAL/license/Frechet_distance.h>
 
 #include <CGAL/Bbox.h>
 #include <array>
 
-namespace CGAL
-{
+namespace CGAL {
+namespace Frechet_distance_ {
+namespace internal {
 
 template <class NT, int dimension>
 class Frechet_distance_traits
@@ -69,6 +69,6 @@ class Frechet_distance_traits
   }
 };
 
+}
+}
 }  // end of namespace CGAL
-
-#endif  // CGAL_FRECHET_DISTANCE_TRAITS_H