diff --git a/Nef_2/include/CGAL/Filtered_extended_homogeneous.h b/Nef_2/include/CGAL/Filtered_extended_homogeneous.h
index 08ea67aaf42..11e67af38c1 100644
--- a/Nef_2/include/CGAL/Filtered_extended_homogeneous.h
+++ b/Nef_2/include/CGAL/Filtered_extended_homogeneous.h
@@ -25,6 +25,7 @@
 #include <CGAL/Interval_arithmetic.h>
 #include <CGAL/Homogeneous.h>
 #include <CGAL/number_utils.h>
+#include <CGAL/tss.h>
 #undef CGAL_NEF_DEBUG
 #define CGAL_NEF_DEBUG 5
 #include <CGAL/Nef_2/debug.h>
@@ -93,14 +94,18 @@ public:
 
 
   // only for visualization:
-  static void set_R(const RT& R) { R_ = R; }
+  
+  static RT& R()
+  {
+    CGAL_STATIC_THREAD_LOCAL_VARIABLE(RT,R_,0);
+  }
+  
+  static void set_R(const RT& r) { R() = r; }
   RT eval_at(const RT& r) const { return _m*r+_n; }
-  RT eval_at_R() const { return _m*R_+_n; }
-protected:
-  static RT R_;
+  RT eval_at_R() const { return _m*R()+_n; }
+
 };
 
-template <class RT> RT SPolynomial<RT>::R_;
 
 template <typename RT>
 int sign(const SPolynomial<RT>& p)
@@ -138,7 +143,7 @@ bool operator<(const SPolynomial<RT>& p1, int i)
 
 template <class RT>
 inline double to_double(const SPolynomial<RT>& p)
-{ return (CGAL::to_double(p.eval_at(SPolynomial<RT>::R_))); }
+{ return (CGAL::to_double(p.eval_at(SPolynomial<RT>::R()))); }
 
 template <class RT>
 std::ostream& operator<<(std::ostream& os, const SPolynomial<RT>& p)
diff --git a/Nef_2/include/CGAL/IO/Nef_polyhedron_2_PS_stream.h b/Nef_2/include/CGAL/IO/Nef_polyhedron_2_PS_stream.h
index c12fd5c2bb6..0662d1bdc8e 100644
--- a/Nef_2/include/CGAL/IO/Nef_polyhedron_2_PS_stream.h
+++ b/Nef_2/include/CGAL/IO/Nef_polyhedron_2_PS_stream.h
@@ -27,7 +27,7 @@
 #include <LEDA/graphics/color.h>
 
 namespace CGAL {
-static int frame_default = 100;
+static const int frame_default = 100;
 
 template <typename CIRC>
 leda_list<leda_point>
diff --git a/Nef_2/include/CGAL/Nef_polynomial.h b/Nef_2/include/CGAL/Nef_polynomial.h
index cf57ef91afe..6b4f276aedf 100644
--- a/Nef_2/include/CGAL/Nef_polynomial.h
+++ b/Nef_2/include/CGAL/Nef_polynomial.h
@@ -29,6 +29,7 @@
 #include <vector>
 
 #include <CGAL/Kernel/mpl.h>
+#include <CGAL/tss.h>
 
 #include <boost/operators.hpp>
 
@@ -70,7 +71,7 @@ class Nef_polynomial
   const Base & polynomial() const  { return static_cast<const Base&>(*this); }
 
     static NT& infi_maximal_value() {
-      static NT R_ = 1;
+      CGAL_STATIC_THREAD_LOCAL_VARIABLE(NT, R_, 1);
       return R_;
     }
 };