diff --git a/Number_types/include/CGAL/Root_of_traits.h b/Number_types/include/CGAL/Root_of_traits.h
index 9fa90959b7b..e8709e047d5 100644
--- a/Number_types/include/CGAL/Root_of_traits.h
+++ b/Number_types/include/CGAL/Root_of_traits.h
@@ -35,14 +35,23 @@ struct Root_of_traits_helper{
     typedef Root_of_2<NT> Root_of_2;
     struct Make_root_of_2{
         typedef Root_of_2 result_type;
-        NT operator()(const NT& a, const NT& b, const NT& c){
+        Root_of_2 operator()(const NT& a, const NT& b, const NT& c){
             return Root_of_2(a,b,c);
         }
-        Root_of_1 operator()(const Root_of_1& a, 
+        Root_of_2 operator()(const NT& a, const NT& b, const NT& c, bool s){
+            return Root_of_2(a,b,c,s);
+        }
+        Root_of_2 operator()(const Root_of_1& a, 
                              const Root_of_1& b, 
                              const Root_of_1& c){
             return Root_of_2(a,b,c);
         }
+        Root_of_2 operator()(const Root_of_1& a, 
+                             const Root_of_1& b, 
+                             const Root_of_1& c,
+                             bool s){
+            return Root_of_2(a,b,c,s);
+        }
     };
 };
 
diff --git a/Number_types/test/Number_types/Root_of_traits.C b/Number_types/test/Number_types/Root_of_traits.C
index 449d3ed2449..7815b9697ee 100644
--- a/Number_types/test/Number_types/Root_of_traits.C
+++ b/Number_types/test/Number_types/Root_of_traits.C
@@ -13,6 +13,13 @@
 #include <CGAL/_test_real_embeddable.h>
 #include <CGAL/Arithmetic_kernel.h>
 
+#include <CGAL/Exact_predicates_exact_constructions_kernel.h>
+#include <CGAL/Root_of_2.h>
+#include <CGAL/IO/io_tags.h>
+#include <CGAL/Lazy_exact_nt.h>  
+
+
+
 template <class T, class RootOf1, class RootOf2>
 void test_root_of_traits(){
     // pure type checking  
@@ -26,6 +33,15 @@ void test_root_of_traits(){
     typedef typename RoT::Make_root_of_2 Make_root_of_2;
     typedef typename Make_root_of_2::result_type result_type;
     BOOST_STATIC_ASSERT((::boost::is_same<Root_of_2,result_type>::value));
+
+    Root_of_2 r = CGAL::make_root_of_2(T(0),T(-1),T(2)); //-sqrt(2)
+    Root_of_2 rl = CGAL::make_root_of_2(T(1),T(0),T(-2),true); //-sqrt(2);
+    Root_of_2 rr = CGAL::make_root_of_2(T(1),T(0),T(-2),false); //+sqrt(2)
+    CGAL_test_assert(r == rl);
+    CGAL_test_assert(rl != rr);
+    
+    CGAL_test_assert( r * Root_of_1(2) == CGAL::make_root_of_2(T(0),T(-2),T(2)));
+    CGAL_test_assert( r * T(2) == CGAL::make_root_of_2(T(0),T(-2),T(2)));
 }
 
 int main(){