diff --git a/Algebraic_foundations/include/CGAL/Test/_test_algebraic_structure.h b/Algebraic_foundations/include/CGAL/Test/_test_algebraic_structure.h
index 581a955b94f..3bb75c865c6 100644
--- a/Algebraic_foundations/include/CGAL/Test/_test_algebraic_structure.h
+++ b/Algebraic_foundations/include/CGAL/Test/_test_algebraic_structure.h
@@ -614,6 +614,9 @@ class Test_is_square {
         typedef typename Is_square::first_argument_type First_argument_type;
         typedef typename Is_square::second_argument_type Second_argument_type;
         typedef typename Is_square::result_type   Result_type;
+        CGAL_USE_TYPE(First_argument_type);
+        CGAL_USE_TYPE(Second_argument_type);
+
         CGAL_static_assertion(
                 ( ::boost::is_same< AS , First_argument_type>::value));
         CGAL_static_assertion(
@@ -647,6 +650,8 @@ public:
     void operator() (const Sqrt& sqrt) {
         typedef typename Sqrt::argument_type Argument_type;
         typedef typename Sqrt::result_type   Result_type;
+        CGAL_USE_TYPE(Argument_type);
+        CGAL_USE_TYPE(Result_type);
         CGAL_static_assertion(( ::boost::is_same< AS , Argument_type>::value));
         CGAL_static_assertion(( ::boost::is_same< AS , Result_type>::value));
         typedef Algebraic_structure_traits<AS> AST;
@@ -670,6 +675,9 @@ public:
         typedef typename Root::first_argument_type  First_argument_type;
         typedef typename Root::second_argument_type Second_argument_type;
         typedef typename Root::result_type          Result_type;
+        CGAL_USE_TYPE(First_argument_type);
+        CGAL_USE_TYPE(Second_argument_type);
+        CGAL_USE_TYPE(Result_type);
         CGAL_static_assertion(
                 ( ::boost::is_same<int, First_argument_type>::value));
         CGAL_static_assertion(
diff --git a/Bounding_volumes/include/CGAL/Min_sphere_of_spheres_d/Min_sphere_of_spheres_d_support_set_impl.h b/Bounding_volumes/include/CGAL/Min_sphere_of_spheres_d/Min_sphere_of_spheres_d_support_set_impl.h
index 8e7c92d69ab..d8878a89ab4 100644
--- a/Bounding_volumes/include/CGAL/Min_sphere_of_spheres_d/Min_sphere_of_spheres_d_support_set_impl.h
+++ b/Bounding_volumes/include/CGAL/Min_sphere_of_spheres_d/Min_sphere_of_spheres_d_support_set_impl.h
@@ -165,6 +165,9 @@ namespace CGAL_MINIBALL_NAMESPACE {
 
         for (int i=m-1; i>0; --i) {
           gamma[i] = beta[i];
+          // the next for won't do anything fori=m-1
+          // which triggers a warning with g++-4.8
+          // but it makes no sense to add an if(i!=m-1)
           for (int j=i+1; j<m; ++j)
             gamma[i] -= gamma[j]*tau[i][j];
           gamma0 -= gamma[i];
diff --git a/Nef_S2/include/CGAL/Nef_S2/Sphere_map.h b/Nef_S2/include/CGAL/Nef_S2/Sphere_map.h
index 3e38d9ee30b..15dbda4bc5e 100644
--- a/Nef_S2/include/CGAL/Nef_S2/Sphere_map.h
+++ b/Nef_S2/include/CGAL/Nef_S2/Sphere_map.h
@@ -158,7 +158,7 @@ public:
     operator SHalfedge_handle() const 
     { SHalfedge_handle e; CGAL::assign(e,Ibase::operator*()); return e; }
     operator SHalfloop_handle() const 
-    { SHalfloop_handle l; CGAL::assign(l,Ibase::operator*()); return l; }
+    { SHalfloop_handle l=0; CGAL::assign(l,Ibase::operator*()); return l; }
 
     operator Object_handle() const { return Ibase::operator*(); }
     Object_handle& operator*() const { return Ibase::operator*(); }
@@ -188,7 +188,7 @@ public:
     { SHalfedge_handle e; CGAL::assign(e,Ibase::operator*()); 
       return SHalfedge_const_handle(e); }
     operator SHalfloop_const_handle() const 
-    { SHalfloop_handle l; CGAL::assign(l,Ibase::operator*()); 
+    { SHalfloop_handle l=0; CGAL::assign(l,Ibase::operator*()); 
       return SHalfloop_const_handle(l); }
 
     operator Object_handle() const { return Ibase::operator*(); }
diff --git a/Polynomial/test/Polynomial/Polynomial_traits_d_Residue.cpp b/Polynomial/test/Polynomial/Polynomial_traits_d_Residue.cpp
index e04d5e67d6c..5ee568e8863 100644
--- a/Polynomial/test/Polynomial/Polynomial_traits_d_Residue.cpp
+++ b/Polynomial/test/Polynomial/Polynomial_traits_d_Residue.cpp
@@ -1,7 +1,6 @@
 #include <iostream>
 #include <cassert>
 
-#include <CGAL/basic.h>
 #include <CGAL/Arithmetic_kernel.h>
 
 #ifdef CGAL_HAS_DEFAULT_ARITHMETIC_KERNEL
@@ -17,7 +16,6 @@ int main()
   // Set wrong rounding mode to test modular arithmetic 
   CGAL::Protect_FPU_rounding<true> pfr(CGAL_FE_UPWARD);
   
-  typedef CGAL::Arithmetic_kernel AK; 
   
   {
     //  Enforce IEEE double precision and to nearest before 
diff --git a/Polynomial/test/Polynomial/test_polynomial.h b/Polynomial/test/Polynomial/test_polynomial.h
index 7612fb16e18..59ab631b23e 100644
--- a/Polynomial/test/Polynomial/test_polynomial.h
+++ b/Polynomial/test/Polynomial/test_polynomial.h
@@ -1,6 +1,6 @@
 
 #include <CGAL/basic.h>
-
+#include <CGAL/use.h>
 #include <CGAL/Test/_test_algebraic_structure.h>
 #include <CGAL/Test/_test_real_embeddable.h>
 
@@ -19,13 +19,13 @@
 #define CGAL_DEFINE_TYPES_FROM_AK(AK)                           \
     typedef typename AK::Integer Integer;                       \
     typedef typename AK::Rational Rational;                     \
-    typedef typename AK::Field_with_sqrt Field_with_sqrt;       \
+    typedef typename AK::Field_with_sqrt Field_with_sqrt;  CGAL_USE_TYPE(Field_with_sqrt); \
     typedef CGAL::Polynomial<Integer> Poly_int1;                \
     typedef CGAL::Polynomial<Poly_int1> Poly_int2;              \
-    typedef CGAL::Polynomial<Poly_int2> Poly_int3;              \
+    typedef CGAL::Polynomial<Poly_int2> Poly_int3; CGAL_USE_TYPE(Poly_int3); \
     typedef CGAL::Polynomial<Rational> Poly_rat1;               \
     typedef CGAL::Polynomial<Poly_rat1> Poly_rat2;              \
-    typedef CGAL::Polynomial<Poly_rat2> Poly_rat3;             
+    typedef CGAL::Polynomial<Poly_rat2> Poly_rat3;  CGAL_USE_TYPE(Poly_rat3);
    
 
 // TODO: copied from number_type_utils.h
diff --git a/Polytope_distance_d/include/CGAL/Polytope_distance_d.h b/Polytope_distance_d/include/CGAL/Polytope_distance_d.h
index 5eed9812674..cd5c4aa1a35 100644
--- a/Polytope_distance_d/include/CGAL/Polytope_distance_d.h
+++ b/Polytope_distance_d/include/CGAL/Polytope_distance_d.h
@@ -574,8 +574,8 @@ public:
   insert( InputIterator1 p_first, InputIterator1 p_last,
 	  InputIterator2 q_first, InputIterator2 q_last)
   { 
-    int old_r = static_cast<int>(p_points.size());
-    int old_s = static_cast<int>(q_points.size());
+    CGAL_optimisation_precondition_code(int old_r = static_cast<int>(p_points.size()));
+    CGAL_optimisation_precondition_code(int old_s = static_cast<int>(q_points.size()));
     p_points.insert( p_points.end(), p_first, p_last);
     q_points.insert( q_points.end(), q_first, q_last);
     set_dimension();
@@ -590,7 +590,7 @@ public:
   void
   insert_p( InputIterator p_first, InputIterator p_last)
   { 
-    int old_r = static_cast<int>(p_points.size());
+    CGAL_optimisation_precondition_code(int old_r = static_cast<int>(p_points.size()));
     p_points.insert( p_points.end(), p_first, p_last);
     set_dimension();
     CGAL_optimisation_precondition_msg
@@ -603,7 +603,7 @@ public:
   void
   insert_q( InputIterator q_first, InputIterator q_last)
   { 
-    int old_s = static_cast<int>(q_points.size());
+    CGAL_optimisation_precondition_code( int old_s = static_cast<int>(q_points.size()));
     q_points.insert( q_points.end(), q_first, q_last);
     set_dimension();
     CGAL_optimisation_precondition_msg
diff --git a/Straight_skeleton_2/include/CGAL/create_offset_polygons_2.h b/Straight_skeleton_2/include/CGAL/create_offset_polygons_2.h
index e70f934b66f..652d19d9ee2 100644
--- a/Straight_skeleton_2/include/CGAL/create_offset_polygons_2.h
+++ b/Straight_skeleton_2/include/CGAL/create_offset_polygons_2.h
@@ -171,7 +171,7 @@ create_offset_polygons_2 ( FT const& aOffset, Skeleton const& aSs, K const& /*k*
 template<class Skeleton>
 Skeleton const& dereference ( boost::shared_ptr<Skeleton> const& ss )
 {
-  CGAL_precondition(ss!= NULL);
+  CGAL_precondition(ss.get() != 0);
   return *ss;
 }
 
diff --git a/Surface_mesh_parameterization/include/CGAL/Fixed_border_parameterizer_3.h b/Surface_mesh_parameterization/include/CGAL/Fixed_border_parameterizer_3.h
index fc8bacfdd4d..d9a020f759f 100644
--- a/Surface_mesh_parameterization/include/CGAL/Fixed_border_parameterizer_3.h
+++ b/Surface_mesh_parameterization/include/CGAL/Fixed_border_parameterizer_3.h
@@ -574,7 +574,7 @@ is_one_to_one_mapping(const Adaptor& mesh,
                       const Vector& ,
                       const Vector& )
 {
-    Vector_3    first_triangle_normal;
+    Vector_3 first_triangle_normal = NULL_VECTOR; // initialize to avoid warning
 
     for (Facet_const_iterator facetIt = mesh.mesh_facets_begin();
          facetIt != mesh.mesh_facets_end();