diff --git a/Bounding_volumes/test/Bounding_volumes/min_sphere_test.cpp b/Bounding_volumes/test/Bounding_volumes/min_sphere_test.cpp
index 82b71269443..ff82ea1bdb0 100644
--- a/Bounding_volumes/test/Bounding_volumes/min_sphere_test.cpp
+++ b/Bounding_volumes/test/Bounding_volumes/min_sphere_test.cpp
@@ -33,10 +33,12 @@
 #include <CGAL/Random.h>
 #include <CGAL/Cartesian_d.h>
 #include <CGAL/Homogeneous_d.h>
-#include <sstream>
-#include <cassert>
 #include <CGAL/Min_sphere_annulus_d_traits_d.h>
 #include <CGAL/Min_sphere_d.h>
+#include <CGAL/Quotient.h>
+
+#include <cassert>
+#include <sstream>
 
 using namespace CGAL;
 
diff --git a/Number_types/include/CGAL/NT_converter.h b/Number_types/include/CGAL/NT_converter.h
index ac225f1e0cb..4a12c4254b1 100644
--- a/Number_types/include/CGAL/NT_converter.h
+++ b/Number_types/include/CGAL/NT_converter.h
@@ -17,11 +17,10 @@
 #include <CGAL/number_type_config.h>
 #include <CGAL/number_utils.h>
 
-template <bool> class Interval_nt;
-
 namespace CGAL {
 
-// A number type converter usable as default, using the conversion operator.
+template <bool>
+class Interval_nt;
 
 template < class NT1, class NT2 >
 struct NT_converter